For the first open assignment I did, I tried color pop. This tutorial was very easy. I learned how to use the history brush and how to desaturate a photo. Tutorial: http://www.digital-photography-school.com/mono-with-a-dash-of-colour-photoshop-cs2-tutorial
For this second open assignment, I chose to do dark art. Dark art is pretty much just making someone's skin looked cracked and almost demonic. I thought this tutorial was pretty easy as well. I learned how to use the burn tool and how to put an image on top of another. Tutorial: http://www.youtube.com/watch?v=Uce-jk-Wlfc