[**BRP (Basic Role-Playing)**][1], the system *Call of Cthulhu*, *Elric!*, *RuneQuest*, and a number of other games use (afaik, as I have actual experience mostly with CoC only, but with that, a real lot) is a system in which successful skill use may lead to the development of said skill. It might fit your needs and requirements.


  [1]: http://en.wikipedia.org/wiki/Basic_Role-Playing