This is the brush I've started to use when sketching. I also used it to draw
There are more of these out there, but I made this one myself. It's quite simple, actually.
I made this is PS CS4, I expect it to work for all other CS versions. Dunno about previous photoshops. Download, open photoshop, open brush tools, load brushes
Oh, and there's no need to link back to me or anything. It's just a simple brush which is easy to make. Do whatever you want with it, even share it with others if you want.