Picnik

Picnik is one of the best free online photo editor. No registration required. It 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. 

Features:

• Fix your photos in just one click
• Use advanced controls to fine-tune your results
• Crop, resize, and rotate in real-time
• Tons of special effects, from artsy to fun
• Astoundingly fast, right in your browser
• Awesome fonts and top-quality type tool
• Basketfuls of shapes from hand-picked designers
• Works on Mac, Windows, and Linux
• No download required, nothing to install

Link to this site: http://www.picnik.com/home