Picnik

For a free image editing site, Picnik was not bad.  My mom is a photographer and I have used her Adobe Photoshop to edit photos before.  For image editing, nothing really beats Photoshop.  I mean it has become a verb for pete's sake!
 

 I'm really going to embrace my "geeky-ness" here.  

The images I chose are from the Backstreet Boys concert I went to this past summer.

Before: 

 After:

I did a couple more just for fun.

 Before:

After:

Picnik would be really fun to use with the teens.  Sometimes I take pictures at our library programs and it would be fun to have them adjust their photos to create scrapbooks or to upload to a teen programming blog.  Since you can add fun words and cute "stickers" to the images I think the teens would really get a kick out of Picnik.  

I did find Pixlr much more similar to Adobe Photoshop.  I think Picnik is much more user friendly but Pixlr has more to offer in the way of image editing.

Here is the image I edited using Pixlr:

I really like the "vintage" feel of this photo.