Cool, who do I use if I want to trade for dollars or euros? I don't have much but I'd like to use them as well.
Intersango also have some of the largest USD, PLN and Euro bitcoin markets, and you can trade with them all from your one Intersango.com account.
For Euro payments you can make a SEPA transfer, it takes 3 days on average and is very cheap, for USD payments we accept Dwolla, also a fast and cheap payment method.