Be very careful if you choose to use this application. I did it one and went through a lot of trouble when one Apple update came up. Since I had removed several languages that I don't use, I could not get Apple to update one of its components. I can't recall exactly which one it was, but I think it was iChat. Because there were components missing, the update for that application would not work. If you don't want several language files added to your Mac, do that during a system installation. Do a custom install and pick the languages you want.

Great. Who needs viruses when we have this? Plenty of Intel Mac users have unwittingly run this software with the default settings and had it kill Rosetta (needed for running PPC apps like Photoshop). AFAIK only an Archive and Install can fix it. BE CAREFUL if you want to use this app. I messed up my system using it and I know others that have too :(

DO NOT USE THIS ON AN INTEL MAC!

Screws it up if you don't select the right settings...

EXTREME WARNING
Do not use this app! Sourceforge forum has long list of complaints from users: apps, computers, OS ruined. Developers do not respond to requests from help on their own forums, for months and months. I wish I had read those complaints before I used this dangerous app. You may be one of the lucky ones whose computer is not radically screwed-up by this app, but don't take the chance. The minimal saving in disc space is not worth the risk.

But is it safe for PPC?

To remove Power PC architectures WITHOUT DESTROYING ROSETTA: in the preferences, uncheck "/system" directory; the app won't touch your system, and you're good to go with only Intel apps.

It freed up a lot of space - in the number of applications it ruined and I had to delete. This should not be released to the general public yet. Do not use it, it's not worth it.

I use this instead:
http://osx.iusethis.com/app/delocalize

try it if you're having problems with this app

Saved 2.2GB here.

I used Monolingual to remove localizations with no apparent problem. The "remove architectures" feature, however, has severely complicated my life. I had to use Pacifist to reinstall a whole lot of random system files from my OS X install dvd to get my MacBook Pro runnning well again. :( I think it also messed up an eMac I was supporting. This was all under OS X 10.4 Tiger.