Definatly s2u2 and Home Customizer which were already mentioned.
But I dont think anyone mentioned PIMbackup which is a must have for me. Automatic backups of contact/message info.
Pocketemu.com is down right now if you cant find the HHC (home customizer) cab let me know Ill attach it but it should be somewhere.
PIMbackup cab.
http://forum.xda-developers.com/showthread.php?t=299705