PicMarkr

picmarkr.jpg Sometimes you need a crucial watermark for your pictures. But what about all of your huge Flickr account? No problem.
PicMarkr allows you to grab them from your Flickr account, or upload them and perform mass batch manipulation. Watermark all of them at once, or one at a time.
It’s free, and you can do it as much as you want with text, image, or tiled watermarking. If you feel like this is a tool that you’ve just been missing out on, then of course the developers would definitely be appreciative of a donation.