Some good apps on that list. Have been using many of them myself for awhile now...and found most of them on my own. To me a lot of the fun, and satisfaction, is finding useful apps on your own.
if you have a multitouch trackpad or magic mouse BetterTouchTool is essential
huge fan of DropBox also.. but its not really mac specific..but it should be on all your computers anyways..it's so handy
evernote: online note syncing and more
adium: multiple chats
dropbox: online file syncing
handbrake: dvd ripper/video encoder
picasa: photo browser and more
chronosync: sync folders through wireless/ethernet
keyboard meastro: hotkeys to apps and more
growl: universal notificactions
sizzling keys: itunes control through hotkeys
last fm: social network costom radio
For me, photography is an important hobby so my top applications revolve around them for dealing with images and producing web pages for said images.
LightRoom
Photoshop
Rapidweaver
Coda
Vmware Fusion (running fedora 12)
AppCleaner; deletes all an application's associated files that wouldn't otherwise be removed if the application was deleted with the trash. Perian; adds support for additional media types in Quicktime. Flip4Mac; adds support for WMV/WMA files to be played in Quicktime.