Fantasy football is a tricky game. An owner has to evaluate a player's worth and guess how long that player will last on the draft board. Reaching for a player is a treacherous error, but taking a player at a decent value position is also bad news if the player would've been there in the following round. Don't overpay.
Here are 5 running backs (in no particular order) I believe provide excellent value:
1) Leon Washington - Jets
Washington is going somewhere between pick 120 and 130, when his worth is much higher. Favre has left the Jets and the increased emphasis on running could wear veteran Thomas Jones down. Washington has proven his worth in the past and will see an increased role this year. He could justifiably be taken somewhere between pick 60 and pick 70, but wait until after pick 100 for exceptional value.
2) Chester Taylor - Vikings
Taylor is being treated as nothing more than an important handcuff for Adrian Peterson, and is being taken too late. Taylor is a good running back on his own, and because he catches and pass-blocks better than AP, he sees the field a lot on 3rd down (and the Vikings see a lot of third downs!). Last year he racked up nearly 800 total yards with a 50/50 split between rushing and receiving. He's lasting until picks 110-120 in many drafts, but is worth the 85th pick. Grab him in the early 100s for good value.
3) Darren McFadden - Raiders
An extremely talented runner on a team whose running game became impressive down the stretch last year, McFadden has a high ceiling. His ADP (according to Fantasy Football Calculator) is 51, but the projections I trust show him worth as high as the 26th pick. Let him fall into the 40s and you'll have a legit RB2 while being able to use higher picks on stud WRs and/or a QB
4) Julius Jones - Seahawks
The Seahawks stank last year. They also had Seneca Wallace throwing to the WRs who were 4th or lower on the depth chart because of injuries. With a healthy Matt Hasselbeck and Housh/Burleson/Carlson, this offense will awake. With Jones being an afterthought for most fantasy owners, you can draft Seattle's feature back at exceptional value. ADP has him going around pick 90, but his projections make him worth the 70th pick. Grab him in the 80s for a solid RB3.
5) Cedric Benson - Bengals
Almost the identical situation as Jones, Benson is pretty much the only RB in an offense expected to improve. ADP has him going somewhere around pick 70, but projections make him worth the 50th pick. Get him in the 60s.
By grabbing a stud RB early, you can use other early picks to load up on talented WRs and a QB while letting these value RB picks fall to you later in the draft. By 'reaching' for undervalued RBs, you can solidify the position on your fantasy roster without sacrificing too many early picks.