try HKN, HotKeyNet. it is also free has the maximiser functionality and a scripting interface = texteditor, but there are lots of example scripts available on the page.
http://www.hotkeynet.com

If you want to have a simple setup try keyclone. it is a one time fee and it works.

If you want heavily do PvP, want a quick window swapping and have some money $36/year go with ISboxer.

They are all pretty useful.

It all depends on your requirements and play style and skills to "set-up" your interface.