I will compile a list of apps that have problems, issues, and force closes in direct result of installing or moving to the SD card. Please reply with your own findings by giving the App name and a short description of the problem.
If any of the below apps are giving you problems, make sure they are not installed to the SD card. To move back to phone storage, go into Settings > Applications > Manage Applications > The App Name > Move To Phone. Some apps deny you the ability to install to SD, but some ROMs can override this.
Do NOT install the following apps to the SD card:
DO NOT INSTALL ANY WIDGET TO THE SD CARD!
Better Keyboard - Android keyboard will set to default unless Better Keyboard is installed to phone.
Car Dock v2 - Android Car Dock will set to default unless Car Dock v2 is installed to phone.
Swype - Android keyboard will set to default unless Swype is installed to phone.
Wireless Tether - Has problems connecting on SD storage.