Bitstamp offers a XRP/USD trading pair. You can even deposit using credit
card from the US. I´m not sure though, whether you can deposit without
verifying your identity. This might take a few days with the current surge of
user registrations.
Nevertheless, I think this is your best option for now, because Coinbase still doesn´t offer
Ripple trading.
Yes, waiting on BS validation for over a week now. Hope it turns around soon.
Between, any confirmed news on Coinbase adding XRP; there were rumors about it, but the topic has gone mute off late.