Universal

Mythic Role-Playing
Assists game masters in creating adventures without preparation. For use as a stand-alone role-playing game or as a supplement for other systems.
http://www.mythic.wordpr.com

Necrotech's Universe of T.W.E.R.P.S.
A space opera setting for The World's Easiest Role-Playing System, presented in English and German.
http://www.twerps.de/

44 Productions
Online store offers Signature, an universal RPG as a PDF download.
http://mysite.verizon.net/resq2tgs/

Wushu
Universal role-playing game with martial arts and pulp era expansions.
http://bayn.org/wushu/