Can I move Applications to another partition?
Just move them is probably the best solution. The user caches and preference files stick with the user home folder, so other than convention - most cases it doesn't really matter which volume contains an application. You'll need sudo or file permission tweaking to actually delete some of the apps, but I've found no downsides to moving any apps to an external drive.



Spotlight still indexes them, updates to the App Store work as long as the drive stays mounted when you want to see that an update is available.

Tools like LaunchBar and others will probably need hand-holding to find your moved applications - especially if you don't place them in /Applications on the destination volume.

You will need to re-introduce the moved copies of the App to Launchbar, but in some brief testing, the following apps worked flawlessly when moved to the root of an external drive.


Mail
iWork 09/Keynote
Utilities/Terminal