Forvo: sounds like a good idea

One limitation of traditional dictionaries is that written word pronunciation suggestions can be pretty cryptic. Forvo offers something a lot better: audible pronunciations of words from more than 170 languages. A couple of caveats:
1. There are less than 1,200 English language pronunciations available so far, most of which are useless, and
2. The pronunciations are user-submitted, so proceed with caution.

However, it's open source, so you can add your own and police any blatant mispronunciations. So even if you don't know how Wikipedia is pronounced, it's kind of like that.