USD to RMB-
I happen to be lucky enough to be a member of a credit union back in the US. I use my ATM card here in China (so far at HSBC, Agricultural, Industrial, and Bank of China) with absolutely zero fee and near ideal exchange rates. This has worked to varying degrees in different countries. The exchange rate is always good, but in Greece there was a $2 fee and in Venezuela $1. It definitely beats Bank of America and the like, which hit my girlfriend for $5 per withdrawal in Greece. So if you happen to have the credit union option open to you I highly recommend it, at least for here.
RMB to USD-
I haven't tried this, but can you set up online payment using Chinese bank accounts? It's a slower process, but if you can pay foreign credit card bills with your Chinese bank then that's another back door route.
On a tangential note, credit cards tend to get ideal rates, but then they charge you 1-3% on top. Some credit card plans are better for this than others. In the US at least, Capital One doesn't charge this exchange fee at all, so I have a nice shiny Capital One card sitting around waiting for me to figure out a way to use it in China. The fee is always listed in the fine print of your agreement under 'foreign currency transaction' or something along those lines.