I saw the "categorization drive" on Commons yesterday, and thought that categorizing 6K images through the usual methods is not fun. Now there are 5K left, and here's my contribution: CatLitter! http://tools.wikimedia.de/~magnus/catlitter.php
The tool with the ultimate name for anything with categories scans [[Category:Media needing categories]], then selects 50 users at random, and shows their images in this category. Many users, especially drive-by uploaders, upload images with a similar content, so that seemed the way to group related images together.
Each image is shown as thumbnail with info, as well as a CatScan list with possible categories, and some standard templates. A textbox contains the image description minus {{uncat}}. Clicking on suggested categories or templates adds/removes the respective item to/from the textbox. The text can, of course, be edited manually. the button opens the diff edit view in a new window/tab.
Have fun, Magnus