I like a LOT of non-traditional stuff, most of it already mentioned here.
Something I have been working on was an M&M conversion of
Dragonstar but this is not even standard DS

mine is going to be a crazy mix of Eberron, Iron Kingdom and Dragonstar...
Basically most (90%) of the history and facts are the same as in the Dragonstar sourcebooks but add in the Dragonmark houses and Technowizardary. In fact there is little to NO traditional technology, everything is created by Arcane Machanika, Scholars and maintained by the Tech Smiths. Warforged instead of Soul Mechs, and War-Jacks are large lumbering machines of death. Guns looks something like a cross between a musket and a modern firearm, while laser and blaster have a more technomagic look and feel powered by crystal-shards.
NOW though I just got True20, along with Blue Rose AND I am seriously thinking of converting it to that system instead

but I am 99% done with the M&M conversion notes right now and it would not be hard at all to convert them over to True20 (as it is somewhat close to M&M anyway).