Here are two RB's that I don't believe are being drafted high enough in the mock drafts that I have seen:
1. Anthony Thomas
2. Kevan Barlow
Not sure that I would call them sleepers, but they seem to fall to later rounds than I think they 'should' be picked.
It is kind of early to be really looking at super deep sleepers, but here is one to watch in preseason to see what the Colts do with him: Dominic Rhodes.
I'm also watching another ex-1000 yard rusher, to see what happens to him: Olandis Gary.