Well since you are a Roy Williams fan I will definitely start by saying that he has the potential to be a top WR year in and year out. He's got size, speed, and strength (as most top WR do). Now I don't know if you mean from this year's draft, but I also think Andre Johnson will be a star in the future (once either the Texans get better, or he gets traded). And many more from previous years (Fitz, Braylon has been good, and more).
As for the young guys (06 draft) definitely Santonio Holmes and Marques Colston, with Colston being #1. He could have had a shot at pro bowl if he wasn't injured. Holmes had 800+ yards in only 4 starts (other games he was #3 WR I believe). We have yet to see Sinorice Moss in a lot of action, and same goes for Chad Jackson, although he is on a team where the WB (Tom Brady) made a lot of diff. WR good ones (or however you want me to phrase that). Oh yea and I forgot Greg Jennings. Definitely either #2 or #3 receiver of this year's draft.