I have always had plenty of complaints with Finder and I don't know if Apple is going to improve it in 10.7, but for the time being, I found a great program that makes Finder into something awesome! It was mentioned on this forum a couple times before but that was during its alpha/beta stages. Its official release is now out, so I figure I'd do a review now that TotalFinder is more mature and stable.
So TotalFinder is now at version 1.1.1 and is actively updated with new features/bug fixes. It is not free, but you have a 14-day free trial to try out the software. The trial is fully featured but it'll have a small watermark on the Finder window. If you like it, it costs $15 or $30 for a three-user license (which would amount to $10 per person if you split it with three people). Here is the developer's website:
http://totalfinder.binaryage.com/
When you install it, you don't have to "run" any new programs or anything per se. It installs as an integrated extension to Finder, so all of the improvements will occur right on top of Finder! This is far more convenient than something like PathFinder, which is not integrated with Finder at all. You will also see a small Menu bar icon at the top right to access TotalFinder preferences/uninstall/update/restart it. If the icon annoys you, you can always hide it, don't worry.
Features:
Tabbed Browsing - TotalFinder finally brings what Finder should have had for a while now. You can use tabs to organize your file browsing:
New tabs can be made via cmd + T. Also any folders you open in Finder will automatically generate a new tab in that Finder window. If you want separate windows for whatever reason, just drag that tab out of the window and it'll generate a new window. One minor issue I have noticed is that there is a little lag if you try to very rapidly create 6-7 tabs or so.
Show System Files - I can't tell you how many times I would like to see some system files or hidden files on my computer (I used Linux before, where it was as easy as a keyboard shortcut to see hidden files). The only way I could do that was do a search with added preferences or run a terminal command. TotalFinder lets me view my system files (and toggle it on/off with a keyboard shortcut). If you're worried about too much clutter, the hidden files will be a lighter/more translucent shade.
Folders on Top - It's a no-brainer that folders should be listed on top of a list, not interspersed between your mess of files. Nevertheless, if you don't like this feature, you can toggle it on/off as well.
Visor - This is something that you'll learn to absolutely love as soon as you really understand what it is. This is what it looks like:
You can click on the Finder dock icon or use a user configurable shortcut to initiate it. The "visor" is basically a Finder window that rolls up and down upon your command. It is really useful because afterword, there is very very little reason to have floating Finder windows anymore. Say you have a number of tabs open, opening/closing the Finder will not close out those tabs, they will still be there when you re-initiate the "visor". The visor will auto-disappear if you click elsewhere but you can pin the visor if you don't want it to disappear either.
Dual Mode - In the following picture, you'll notice two tabs are fused to make a dual mode view. This is convenient if you need to drag files to another folder. You can toggle the view on/off with a keyboard shortcut. Even more conveniently, if you have two tabs you want to go to dual mode with, just double click on the left of those two tabs and they'll fuse.
Cut/Paste - Losing cut/paste is really frustrating because you can't move files without dragging them. This is a pain because you have to then have both Finder windows open at the same time or use OS X's spring-loading feature, which still isn't as convenient as cut/paste. With TotalFinder, you get that functionality right in the standard context menu (or via cmd + x).
Asepsis - If you are annoyed by all the .DS_store files on your computer, TotalFinder can install .kext that redirects all those .DS_store files to one centralized location but won't break anything either.
This is what the preferences window looks like:
It actually just creates a new tab in your Finder preferences. You can configure all your features and keyboard shortcuts here.
Conclusions: This extension of Finder is a great program. I've been playing with it quite extensively for a while now and I haven't noticed any increased CPU usage by Finder or any sluggishness in doing any folder/file actions. Of course, it is perfectly acceptable to say that these are features that Finder should have come with already, but right now, this is the most convenient way to extend Finder's functionality. The only cons include that slightly sluggish behavior when initiating a large number of tabs simultaneously and while I have had 0 problems stability-wise, a few people have, so its important to try it out first. You can easily uninstall to revert back to the original Finder, so no worries either!
So TotalFinder is now at version 1.1.1 and is actively updated with new features/bug fixes. It is not free, but you have a 14-day free trial to try out the software. The trial is fully featured but it'll have a small watermark on the Finder window. If you like it, it costs $15 or $30 for a three-user license (which would amount to $10 per person if you split it with three people). Here is the developer's website:
http://totalfinder.binaryage.com/
When you install it, you don't have to "run" any new programs or anything per se. It installs as an integrated extension to Finder, so all of the improvements will occur right on top of Finder! This is far more convenient than something like PathFinder, which is not integrated with Finder at all. You will also see a small Menu bar icon at the top right to access TotalFinder preferences/uninstall/update/restart it. If the icon annoys you, you can always hide it, don't worry.
Features:
Tabbed Browsing - TotalFinder finally brings what Finder should have had for a while now. You can use tabs to organize your file browsing:

New tabs can be made via cmd + T. Also any folders you open in Finder will automatically generate a new tab in that Finder window. If you want separate windows for whatever reason, just drag that tab out of the window and it'll generate a new window. One minor issue I have noticed is that there is a little lag if you try to very rapidly create 6-7 tabs or so.
Show System Files - I can't tell you how many times I would like to see some system files or hidden files on my computer (I used Linux before, where it was as easy as a keyboard shortcut to see hidden files). The only way I could do that was do a search with added preferences or run a terminal command. TotalFinder lets me view my system files (and toggle it on/off with a keyboard shortcut). If you're worried about too much clutter, the hidden files will be a lighter/more translucent shade.
Folders on Top - It's a no-brainer that folders should be listed on top of a list, not interspersed between your mess of files. Nevertheless, if you don't like this feature, you can toggle it on/off as well.
Visor - This is something that you'll learn to absolutely love as soon as you really understand what it is. This is what it looks like:

You can click on the Finder dock icon or use a user configurable shortcut to initiate it. The "visor" is basically a Finder window that rolls up and down upon your command. It is really useful because afterword, there is very very little reason to have floating Finder windows anymore. Say you have a number of tabs open, opening/closing the Finder will not close out those tabs, they will still be there when you re-initiate the "visor". The visor will auto-disappear if you click elsewhere but you can pin the visor if you don't want it to disappear either.
Dual Mode - In the following picture, you'll notice two tabs are fused to make a dual mode view. This is convenient if you need to drag files to another folder. You can toggle the view on/off with a keyboard shortcut. Even more conveniently, if you have two tabs you want to go to dual mode with, just double click on the left of those two tabs and they'll fuse.

Cut/Paste - Losing cut/paste is really frustrating because you can't move files without dragging them. This is a pain because you have to then have both Finder windows open at the same time or use OS X's spring-loading feature, which still isn't as convenient as cut/paste. With TotalFinder, you get that functionality right in the standard context menu (or via cmd + x).
Asepsis - If you are annoyed by all the .DS_store files on your computer, TotalFinder can install .kext that redirects all those .DS_store files to one centralized location but won't break anything either.
This is what the preferences window looks like:

It actually just creates a new tab in your Finder preferences. You can configure all your features and keyboard shortcuts here.
Conclusions: This extension of Finder is a great program. I've been playing with it quite extensively for a while now and I haven't noticed any increased CPU usage by Finder or any sluggishness in doing any folder/file actions. Of course, it is perfectly acceptable to say that these are features that Finder should have come with already, but right now, this is the most convenient way to extend Finder's functionality. The only cons include that slightly sluggish behavior when initiating a large number of tabs simultaneously and while I have had 0 problems stability-wise, a few people have, so its important to try it out first. You can easily uninstall to revert back to the original Finder, so no worries either!