I'm going to be very honest here and say that this was not my strong point in drafting. I watched very little football last year, so I was mostly dependent on draft cheat sheets and sleeper articles. Most of my success came out of building a solid draft plan and following it. I ignored all of the advice saying to draft Kurt Warner if you couldn't get Faulk, Alexander, or Green, for example. I concentrated on stud RBs first, then WRs, and found QB steals like Tom Brady (Superbowl MVP, let's be real) after most people had drafted their starting QBs.
For sleepers, I made alot of mistakes. I drafted the likes of Johnnie Morton, Brian Finneran, etc., and ended up having to dump them.
I more than made up for my draft day mistakes by watching the games, checking stats, and picking up high potential free agents before they did enough for other people to pay attention. Therefore, I ended up replacing Morton and Finneran with guys like Peerless Price and Marc Bulger.
I'd say my best "sleeper" draft pick was RB Fred Taylor in Round 10 of a Yahoo league draft. I was every bit as thrilled however to get Marshall Faulk with the #4 pick in one autodraft (10 people drafted QBs in Rd 1, trying to get Warner or Garcia, lol). Getting Priest Holmes with the 12th pick in another league was also a big shot in the arm.
My opponents often drafted some late round talent, including Travis Henry in Round 10 and Marty Booker in Round 12.