uControl for Mac

From gnufoo.org:

uControl is a keyboard remapper and more. Meaning, those useless keys can now be reused, remapped, or reduced. Unix hackers will be pleased to remap the caps lock key to the control key. Indeed, that was the reason uControl was originally created; however, it has since evolved into a fairly sophisticated means of not only remapping modifier keys, but providing a virtual scroll wheel for trackpad users, providing real function keys for laptop users, swapping the right and left mouse button for left handed users, and even providing a one handed typing feature for those with disabilities. Note: the one handed typing feature has been removed due to possible patent infringement.