I used fantistics.com last year. You have to pay for their software, but it allows you to put in your league settings, and then it generates auction values based on projections it updates daily before the start of the season. It also allows you to weight position players versus pitchers depending upon what you think your league values. You can also manually edit individual player values based on what you think owners will pay for them.
During your actual draft, it will automatically update values for players on the fly based on who has been taken and at what price, and depending upon what positions you still need to fill.
I thought it was fantastic for knowing who I could outbid on which players, and for predicting when a player was just trying to run up the price on someone (someone tried to run up Jeff Franceuor on me, and I was able to counter run it up to $31 and stick him with him last year!!) It also gives you realtime updates on how much cap each team has left, and I think it does a good job on player projections.