Installing programs on an external hdd...?

[superspiffy]

I'm running out of hdd space pretty fast on my 120gb MBP. I'm using 60gb of it for Boot Camp (and no I can't make it smaller) and all the rest are for OS X apps. All my pictures, movies, and music are already on an external.

Is there a way I can start installing programs on my external hdd? Is there a program that can do this? Or is there a program that "spring cleans" my hdd freeing up a few gigs? Preferably free.

 

[rdowns]

YOu can install programs on any drive you want. You just indicate which drive when installing it or dragging the program file to the appropriate drive.

You can delete unused printer drivers and language files from your internal drive and save 1-2 GB. Try Delocalizer.

 

[superspiffy]

YOu can install programs on any drive you want. You just indicate which drive when installing it or dragging the program file to the appropriate drive.

But I thought it won't let you install on a drive where OS X is not installed. When installing programs, my 2 external hdds always get the red exclamation mark and my internal hdd gets the green go ahead signal.