You can now link a U.S. bank account to SnapSwap.us and use that to directly transfer funds into your Ripple wallet. In fact, OpenCoin themselves is giving 1k XRP to anyone who verifies their bank account on SnapSwap.
I personally did this and put 200 USD into my wallet to test it out. Took 2-3 days but didn't have to deal with excess wire fees or anything like that. I think I paid something like $2.80 to SnapSwap for the transaction which is significantly lower than any other option I've dealt with for getting funds to a BTC exchange.
I did this as well, but now I'm stuck. I can't figure out how to convert those USD to another currency (or XRP). How do you convert from one currency to another within the ripple wallet?