Worth 1000 is a website where folks compete in photography and photo manipulation. I haven't been here for a while, and it looks like they've redesigned the site. It also looks like they are more closely associated with the Aviary online tools.
I often come here when I am trying to come up with ideas for my Multimedia classes. I've adapted some of the contests I've seen here into classroom lessons. I don't usually visit the site live during class, as there can be inappropriate for school content. They've also added a multimedia section that I don't remember seeing before that includes other media such as sound. Use your judgment on using in the classroom based on the level of your students.
Here is a recent illustration contest: Literary Scenes - Worth1000 Contests. The scene above was taken from this slide show and is called "The House of Usher" by bajazet.