go to terminal emulator and enter
pm setInstallLocation 2 (enter)
It will do nothing just exit.
U can now move most apps to sd card under settings.manage apps. Move to sd card!
May be issues like widget doesn't load. So try it and discuss!
Must be running froyo, must be rooted, follow command exactly.
After playing with it for a few hours I suggest only changing apps that are standalone such as games.
Leave the home replacements, active task killers, widgets or anything running in the backround.
After a reboot it may look like ur apps are gone. Just give them time to load from the sd card.