Currency Fair. Takes a bit of setting up but a very small charge per transaction ($3) and better exchange rate than the banks. Tells you how much better off you are by using them.
Would agree with Currencyfair, especially if you have time on your side and don't need to send it immediately.
It works a bit like betfair, in that you are dealing with other customers and the rate they set. You can set a rate that is a bit better than the current exchange rate and if it is met, it will automatically go through. If the exchange rate changes, you can alter your rate (presuming nobody has already accepted)
As mentioned above, there is a small charge per transaction, but NO commission.