I wouldn't call Call of Cthulhu lesser known, just lesser played. <.<
Numenera's fairly new (but I've had it longer than it's been available to the public, so my time is skewed a little). I still haven't seen it in stores and stuff, so I'd probably have to supply a homebrew lite ruleset. -_- Only thing I'd have against doing it. (But that shouldn't be too hard; it's a fairly easy system, and I suppose I could just let people make their own stuff with the given rules, with some supplied examples).

Anyway, yeah...