for general:
3g/2g/dual mode selection applet
caller ID state Switcher Widget
callnotify
camkeyd
Cellular Modem Control Buttons
cpufreqUI
Custom Operator Name Widget
D-THEME (any of them work great)
DateToday Home Desktop Widget
Documents To Go Viewer Edition
Flashlight
FM RDS Notify
fm-boost
healthcheck
Joikuspot
lockdaemon
Sygic Mobile Maps
morphoquickpanorama
Ogg Support
Petrovich
recaller (to record phone calls when needed for note taking)
Recorder
Simple brithness Applet
Search Tool
Simple FMTX desktop widget


for musicians:
maetronome (skips beats every so often, but works great to get the tempos)
Tuner


for advanced:
Easy Chroot
Easy Debian
Enhanced Linux kernel for power users (i have had my unit overclocked since it started. Battery is actually better at 900mhz then stock, and it a about the same as stock at 1.15ghz)
Midnight Commander
rootsh