Version 6.0 of Adobe's Photoshop Elements still has problems when running under non-admin accounts. On my computer, none of the effects or layer styles would appear in the Effects palette. It appears that PSE6 needs to write to a file called MediaDatabase.db3 in order to load the effects. Allowing write access to this file for non-admin users fixed my problem.

To fix the permissions, run the following command in Terminal while logged into an admin account, and enter your password when prompted: Note that if your copy of PSE6 is not set to US English, then you will need to change en_US to the appropriate folder name.