Dumpr

On dumpr.net you can add all kinds of cool effects to your pictures. Most of the effects are free, but some require you to register a pro-account. You can upload a picture from your computer to add an effect on, or you can upload the picture from Flickr. After you've added your effect to the picture, you can download it, send it as an e-mail or upload it to Flickr. Registering an account is possible, but not needed.