The Unidentified Flying Raw (UFRaw) is a utility to read and manipulate raw images from digital cameras. It can be used on its own or as a Gimp plug-in. It reads raw images using Dave Coffin's raw conversion utility - DCRaw. UFRaw supports color management workflow based on Little CMS, allowing the user to apply ICC color profiles. For Nikon users UFRaw has the advantage that it can read the camera's tone curves. Even if you don't own a Nikon, you can still apply a Nikon curve to your images.
The Rasterbator creates huge, rasterized images from any picture. Upload an image, print the resulting multi-page pdf file and assemble the pages into extremely cool looking poster up to 20 meters in size.
Flickr Backup is a Java application that allows you do download your photos and back them up to your harddrive or to media. This is useful if your local harddrive goes bad and you don't have a current backup.
SmillaEnlarger is a small graphical tool ( based on Qt ) to resize, especially magnify bitmaps in high quality. ( The used algorithm is an invention of my own )