another +1 for swiftkey x. i somehow never really got used to swype despite trying it several times, but i'm really happy with swiftkey.
a few other apps that i really like and that haven't been mentioned (some of this is directed to newer android users):
- mighty text: send text messages from chrome browser, call notifications in chrome and so on. very useful if you use chrome
- i LOVE the autorotation control app (
https://market.android.com/details?id=com.norightrotate). it's a super simple app that lets you automatically deactivate a specific "auto-rotation". i often lie in bed on my right body side and read tweets & stuff and don't want the screen to rotate. and with this app, it never does. (i just deactivate the right turn rotation and if i want the phone to rotate, i just rotate it another 180°)
- depending on what phone / skin you have, i recommend a different dialer. i still think the htc sense dialer is probably the best, but the standard android aosp is unfortunately rather bad. right now i use touchPal dialer (not really that big a fan of its layout, but it does its job nicely)
- alternative video player that work better with xvid / mkv files: rockplayer, moboplayer)
- tasker (more info in old thread and on their website). i don't use it extensively, mostly just for automatic (de-)activation of wifi and to start music player (and set the media volume) if i plug in headsets
to the guy that asked about the galaxy s2: everyone i know that has this phone REALLY loves it. it was definitely the best android phone when it came out in europe a few month ago. it seems that for people in the US, there are by now some interesting alternatives, so it's more a matter of taste.