Rippletrade also allows to "convert" (which makes an effort to find the best rates currently available).

You might want to read up on RSC first, before you start "mining" it and expecting any kind or ROI. It is more a way of mirroring your BOINC stats into Ripple while hoping that someone might want to donate money by paying for these (essentially useless) points.

If you already own RSC, you can also just type in a BTC address in Rippletrade, it should automatically use the Bitcoin bridge operated by SnapSwap and let you pay with whatever currency has a path towards BTC.SnapSwap (RSC amongst others).