UFRaw

UFRaw is an application that is designed to help you view and apply various adjustments to RAW files obtained from digital cameras.
Unidentified Flying Raw (UFRaw) can also be used as a Gimp plugin, thus giving you even more freedom to edit the file after you convert it to a more common format. Whether you use it as a standalone application or a as a plugin, UFRaw can help you process RAW files such as Canon CRW/CR2, Nikon NEF/NRW, Pentax PEF, Fuji RAF, Olympus ORF, Minolta MRW, Sony ARW/SRF/SR2, Samsung SRW and Sigma X3F.
Basically, all cameras from consumer to professional level are covered, which is great news if you tend to use cameras from multiple manufacturers. On the other hand, since every manufacturer has its own sensor type, each one encodes its RAW file differently meaning that no two identical photos taken with different cameras look the same when loaded into the application and unless you’re an expert, they won’t look the same when exported.
Until you get to that point, UFRaw has a large set of tools to help you obtain the best result from your RAW files. It provides you with the much needed histogram that enables you to get a clear view of color and light distribution. You also get to to toggle warnings for overexposed and underexposed areas of the photo so you can correct them.
UFRaw also provides you with a set of tools that you find in top of the line RAW processing tools such as lens correction, base curve, color management, luminosity and saturation correction, lightness adjustment, crop and rotate. From a functionality point of view, the all work as they should, but the controls themselves seem a bit rough around the edges.
All in all, to get great looking photographs you have to practice and the same principle applies to using UFRaw. You have to use it a few times and really go into the details to see what it can do.