Instead of task killer I use Advanced Task Manager, it is $1 but its my most used app so I shelled out the buck for it. It works amazingly.
I like
Babbler (the only actual usable facebook app)
Tune Wiki (Music player with MANY great features)
K-9 (mass email box, only app I know of that is compliant with hotmail)
Phonalyzer (gives you call data and statistics)
The Weather Channel (duh)
Quick Wi-Fi (for quick on and off)
Flashlight (I actually use it soooo much)