Where can I meet like-minded people interested in solving the same problems as me?
Under certain circumstances, I and some of my colleagues would be looking for joint ventures. But what we'd bring to the table specifically would be online property – i.e. domain names. That would require a very compelling project, though, and a coherent business plan.
I realize that's not quite what you're asking for. But there's a 10% chance it may be relevant to your business idea – or to someone else in a similar position.
Personally, I'm also on the lookout for interesting projects where I could act as a minor partner, contributing branding help, copy, and perhaps legwork. I'll be rolling out a few collaborative projects like that with other primary entrepreneurs in the next couple of years.
Again, that's probably not an exact fit for you. But you asked about places to meet collaborators, and one such place is right here.