Apps
AppBrain App Market: perfect to keep all apps up-to-date
Barcode Scanner: Bit useless once you have all the apps you want
Beautiful Widgets: Love the clock/weather widgets
cab4me: Perfect if you need to find a cab
Camera 360 Pro: Best camera app...and it's not even close!
Chrome to Phone: Easily share links/text/pics from your computer
Dolphin Browser: Best browser imo...very fast and good bookmarks
doubleTwist: Replaced iTunes completely
ES File Explorer: prefer it over Astro
FeedR: My favorite RSS app, great widget
Google Translate: I travel a lot, and don't speak Arabic
K-9 Mail: Best email program
London Journey: Tube/Bus journey planner rocks!
Meebo IM: My favorite IM app
Navigation: A must if you got a car!
Reuters News Pro: I love that I can download all articles at once before a long flight
PingChat!: I got friends all over the world, this cut down costs of SMS a lot
Pure Grid Calendar: Best calendar app (love the widget)
ShopSavvy: Best way to compare prices while out shopping
SlideIT keyboard: Best keyboard app
Spotify: Free music...I got the premium access because I like to have offline playlists
SwiFTP: No more USB cables required when transferring files to my computer
TED: Hooked on those videos!
TubeMate: Download Youtube videos
Voxofon: Suuuuuper cheap international calls
Widget Locker: Best locker replacemant
Yelp: Looking for a burger joint, use Yelp
Launcher Pro Plus: Best home replacement, and the widgets rock...can't wait for the FB widget
First Aid: A must imo...just in case you ever need to help someone and don't know how
Dropbox: A MUST HAVE! Cool to transfer files, and saves space because I can just download stuff whenever I need it instead of having it on the SD card all the time.
Games
Angry Birds: Ok, just one more try! It eats my time!!
Falling Ball
Guns'n'Glory
Those are just the apps I use regularly. Layar, Google Goggles and a few others are cool too, I just don't use them that often.