I've attempted to use StackOverflow, but by the time I have questions difficult enough to go there they're well above the level that SO is capable of answering. (At least, not without bribing people with rep, which I don't have because I don't use StackOverflow.) So it's pretty useless to me.

As for GitHub, I've downloaded libraries from it, but I have a pretty healthy dislike of Git, which is awful, and refuse to use it for any personal projects. (I only use it at work because I have to-- in any case, work repos are of course private.) I used to have a few projects publicly available on Google Code, but now that's shut down, so there's really just nothing. I do have private repos for my hobby work.

In case it matters, most of my development is in C#.NET.