The popular open source RAW converter UFRaw recently gained new functionality when it was bumped up to revision 0.12. The new release integrates new core image-processing functions and new user interface features to simplify photo editing.
If you want to try the software for manipulating your digital camera's RAW images, you can download UFRaw source code tarballs. Check the installation instructions for any external dependencies you need to acquire separately -- in particular, the program's new scrollable preview window uses the GtkImageView widget, which is not yet supplied by several Linux distributions. You can compile UFRaw just fine without GtkImageView, but the ability to scroll around a zoomed-in image preview is handy, so the widget is worth pursuing.