I just joined Pinterest and it is awesome!! All my favorite artists are on my "board" and I've even discovered others artists whose work I admire. I can spend hours on there looking up and pinning artwork and photos to my board.
Not many people know of Anne Bachelier, but her work in on Pinterest! I was amazed! My own work is even up there. That was a surprise!
There are the most beautiful photographs of people, nature, animals, celebrities, models, etc. on there and even comic strip art. Basically, whatever image you can find on the internet can be added to Pinterest.
You can even add a button on your toolbar so you can add images from the internet onto Pinterest.
I added the app to my phone so I can browse through my favorite images and add new ones while I'm away from home. It's crazy.