Source: http://feeds.gawker.com/~r/lifehacker/full/~3/217333655/namexif-batch-renames-digital-photos-by-date
Windows only: Photo file utility Namexif renames your digital pictures based on the timestamp they were taken, plus a custom name (like an event description). Point Namexif at a directory of photos, and it reads the EXIF metadata your digital camera stores with the photos, and renames the files from your camera's default IMG_7934.JPG to the date in a format you choose, like 2008-01-01-New Year's.jpg. Very handy, especially for processing huge batches of photos from vacation or the holidays. Namexif is a free download (donations welcome) for Windows only.
