Do you know of any good art reference sites?

I need to improve my speed drawing skills. I normally do pencil sketches and have recently started drawing in pen as well, but I need websites with reference for me.

I enjoy drawing people and human anatomy. I have also found that tattoo stencils serve for good drawing exercises. They don’t need to be photos, they can be sketches other artists made as well. If any fellow artists know of any useful websites with a wide variety of reference, please let me know.

P.S. I will and do not claim the works I use as reference as my own unless they ARE. I merely use them as exercises.

Thank you. 🙂