Ok, i have a few hints i figured out and some comments on previous posts...
We all know that the bulge on the headphones cord can pause/play the current song. Double-squeezing also skips to the next song... But here's the cool thing: If you aren't using iPod at all (or if it crashes when you try to send a txt or use the web), and want some music, you can start up iPod mode with a double-squeeze --> then a single squeeze to start the music playing. It will automatically start playing the first song in your Songs list, and work it's way through. I wish it would pick up where it left off, but hey, something is better than nothing!
Page down. When not using a zoomed-in display, double-tap towards the bottom of the screen. The page will re-center around your tap. Make sure not to tap a link!
Actually, you can double-tap a link, without linking it. Double-tap anywhere to zoom in.
Jump to the top. Double-tap the very top of the screen, just below the time display to pop back to the top of the page. (Thanks John C)
This also shows the URL bar, and makes it easy to enter a new address.
Zoom onto a single picture. Double-tapping images in Safari zooms them to fit your iPhone display. If the picture is linked to a URL, this can prove a little tricky but it works great for non-linked images. Double-tap again to return to the unzoomed display.
It doesn't matter if the picture is linked or not. double-tapping will zoom, and that is all.
This is a google maps trick that is even more helpful when using the iPhone. Typing in the three letter airport code while in maps will bring the airport up on the map.
The Maps app seems to be pretty smart in general. I do a lot of searching for things in town without adding my city, state, or zip. I'm not sure it searches in relation to your last search, or what is currently in the view port, but it seems to check the "local" listings first! That saves a ton on typing.
Also, after a restore, the Maps app seems to know where you are. We need to find a way to be able to do this at will...
OK, here's a few more that i think are obvious, but someone may have missed...
when browsing photos, you can flick a photo to the right or left to advance through the album, as long as you are zoomed out. You can do it slowly, and see the next photo coming in.
You can flip through your notes using arrows at the bottom -- you don't have to keep going back to the main list screen (like i was doing for 2 weeks).
If you need to save a number when on a call, you can kinda use the calculator. It will save the last number you put in, even if you open other apps... however, the Memory feature doesn't save values if you go home, and then back to the calc. also, it only holds 9 numbers, so don't put in the area code, if you can help it! --- of course, the Notes app works too, but i like the bigger buttons if i just need to jot a number.