Under "The Commons," cultural institutions that have reasonably concluded that a photograph is free of copyright restrictions are invited to share such photograph under their new usage guideline called "no known copyright restrictions."
Picnik makes your photos fabulous with easy to use yet powerful editing tools. Tweak to your heart’s content, then get creative with oodles of effects, fonts, shapes, and frames. It's fast, easy, and fun.
GIMP - The GNU Image Manipulation Program. This is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems and in many languages. It is similar to Photoshop. It can take some to learn how to use.