Other modding/hacking scenes?

I'll drop a link to JUMP here, it's probably my favourite SMW hack. It takes some of the unfettered creativity of the older SMW hacks, but keeps it tempered with quality almost all of the way through. Be careful though, since the difficulty shoots up halfway into world 2, and you'll probably wet your pants every time you see that "morcel/morceau" is the creator of a level.

http://www.smwcentral.net/?p=section&a=details&id=13512

I also like Zelda Parallel Worlds. It's in a bit of an awkward position for some people since it's more difficult than people expect from a Zelda game, which causes many fans of vanilla to shy away. But other than a couple hitches (the parallel tower in particular is way too long and you go through it too many times), I feel it falls under "tough, but fair". I haven't checked in a bit, but it's also the most complete LTTP hack that I've found in general.

http://www.romhacking.net/hacks/197/

I'm ignoring the hacks from Insane Difficulty (http://www.insanedifficulty.com/) since half of you have probably been there anyways. But most of those hacks are gold.