The UFRaw (Unidentified Flying Raw) is a tool for reading and manipulating raw images from digital cameras. It supports most of the existing raw formats (any format supported by DCRaw). UFRaw can be used on its own or as a Gimp plug-in.
powerful, full control of workflow, only missing some features
UFRaw makes it easy to access RAW files under Linux - fantastic that I don't have to use proprietary software to use my camera.