Tool for creating .rar files on the Mac? Is there any good, free program for OS X that can create RAR files? Preferably with a GUI.

It seems there are plenty of options for extracting RAR files, but not that many for compressing them...
You can use command line rar for Mac OS X, but it doesn't have GUI. On the other hand, it's useful for scripting. (I feel that it should be mentioned here anyway).