darktable is an open source photography workflow application and RAW developer. A virtual lighttable and darkroom for photographers. It manages your digital negatives in a database, lets you view them through a zoomable lighttable and enables you to develop raw images and enhance them.
For Ubuntu (11.04), type the command in Terminal.
sudo add-apt-repository ppa:pmjdebruijn/darktable-release
sudo add-apt-repository ppa:pmjdebruijn/darktable-release-plus
sudo apt-get update
Then Search "darktable" in Ubuntu Software Center to install.