Yet another SE I'm joining; damn, this is addictive!

So, here's the situation: I'm a moderately (10+ yrs) experienced Web Developer (mostly front-end, though and lately evolving into kind of a creative planner) with a full-time job and a never ending stream of more or less original, more or less cool ideas for software/apps/stuff yet to be written on my mind.

Sometimes, I go like "screw it, I'm gonna try to code this now" and start … coding. Several hours later, I end up with a decent more-or-less-working prototype of what I'm trying to build. Then, my alarm clock goes ringing and I have to get back to the real world, tired as hell. In most cases, the stuff I started remains unfinished forever. Sometimes, that's okay. Other times, I honestly feel like that's a bummer.

But hey, there's open source, there's github and the like, there's a zillion of other coders out there … wait … where exactly are they?

So, (also, tl;dr): Is there a place you know of where one can post ideas/proposals/concepts/rough-around-the-edges-code in order to find people who are interested in collaborating on projects?