What is your favorite unrecognized (and undocumented) File Exchange submission?

Hi there, I'm a big fan of the "Pick of the week" blog . This week Brett had the very good idea to let the user pick one up ( http://blogs.mathworks.com/pick/2012/04/13/what-is-your-favorite-unrecognized-file-exchange-submission/). However the rules or I shoud better say the new added rule don't allow undocumented functionality to nominate. So I'd like to know: what is your favorite unrecognized and mostly based on undocumented functionality File Exchange submission?