Nice thread. Was going to post something like this myself.

Here's some stuff I did so far: (just what I can think of at the moment. =P)

1. Customer Operator Name - easy
2. Remapped all the symbols to the hardware keyboard.
3. Installed mscim and mscim-hangul for native Korean input
4. Camkeyd - camera key for task switcher
5. Flashlight - Use your camera LED as flashlight
6. cpumem applet - display cpu/mem status icon
7. Created custom folders and rearranged some main menu icons.

8. Desktop Command Execution Widget - display accurate battery %.
http://img189.imageshack.us/img189/6...0010412072.png
9. Cellular Modem Control buttons
10. Droid Fonts - Better font for xterminal + CJK font support
11. Extra decoders support - supports avi with AC3 audio for example.
12. mplayer + SiB frontend = The best video media player combo.
13. OpenSSH - to be able to ssh into my phone wirelessly.
14. Petrovich - to easily send any file over bluetooth
15. Powatool - delete intro video and remove stuff from sys memu
16. rootsh - type "root" to gain root access in xterminal
17. Simple brightness applet - quickly change LCD brightness
18. Simple FMTX desktop widget - turn radio transmitter on/off quickly
19. Unzip add-on for file manager
20. Wiicontrol - use wii controller to play snes games
21. Enable reboot button in the power button menu.
22. Changed the Touch screen vibration feedback "feel/strength".
23. Transition control app (see below)

If you want the transition between portrait and landscape smoother and quicker:

1. Install the transitioncontrol app. (extras-devel = know the dangers)
2. Change the following values to:

Rotate% = 85
Rotate In = 25
Rotate Out = 25
Blank min = 0
Blank max = 0

3. Hit apply changes button.
4. Now enjoy a much faster but still very nice looking phone app transition!

Feel free to mess about with these settings untill you get what you want.
I've opened / closed my N900 about 100 times to get above numbers. =P