There are gateways which accept bitusd and give usd

Link?

https://metaexchange.info Off top ofhead for usd and i developed this site http://cryptosmith.info for gold and. Silver gateway

The link only shows pairs for BTC. Where is bitUSD/USD?

bitstamp or snapswap ripple USD Being built but you can use metaexchange for now and go thru bitstamp. Ccedk.com also have fiat accounts