I ran across a neat site today (it's not new, but was new to me) while perusing LifeHacker . it's called howjsay.com , and all you have to do is type in the word you'd like to hear, and it pronounces it for you. pronunciation is in standard British English, so "aluminum" comes back with the American and the British pronunciation (the Brits say "al-u-mi'-neum). I couldn't come up with a word that stumped it. According to the site:
"The lexical corpus includes all of the General Service List (Bauman and Culligan 1995 version). This is a collection of 2,284 commonly used English words."
It's also available as a search plug-in  for Firefox. Oh, and in case you were wondering, it contains no profanities, so is kid-friendly.