RAWStudio is a free RAW processing application for processing digital SLR camera RAW files.
RAWStudio utilises DCRAW for reading RAW files. This means it is cabable of converting RAW formats from Canon (CRW, CR2), Nikon (NEF) and many others. For the complete list visit DCRAW's page to see the supported cameras. This page is geared towards developers.
RAWStudio has quite a pleasant usable interface with the processing options tucked away on the right hand side.
Unfortunately it seems there are no available binary downloads so the only available downloads are with Linux disctributions. For instance on Fedora 8 you can just run 'yum install rawstudio'.