There's a few options for finding programmers:
This is a more professional, less community oriented site that offers freelance programmers for hire.
This is a site that programmers particularly like, and it's more of a community. There is a jobs board here to find programmers to hire, too.
The same problem exists with both sites, however: There is no way of knowing whether or not the programmer is good. Just remember the cautionary tale of the Winklevoss Twins and Facebook. It's easy to come up with ideas, but the actual implementation is what's most important. There is always that risk of someone else running off with the idea, but it could turn out successful too.