NetRadiant is an updated version of GtkRadiant 1.5. You can get an intel OS X version from the NetRadiant site, http://icculus.org/netradiant/, or there's a universal binary version that you can get from http://ingar.satgnu.net/gtkradiant/index.html#osx.

Here are the .map files for my two Movie Battles II maps: Doomgiver and Raxus.
Feel free to do anything with either of them.

If you're having problems running a Quake 3 engine game on a MacBook (if it makes a strange buzzing noise when it's starting up), try putting this autoexec.cfg into your base/baseq3/etmain/whatever it's called folder.

I've released v0.2 of my Jedi Academy script compiler, you can get it from here. It needs OS X 10.4 or greater.