All of these sites are great, free sites, so check them out if you get a chance:
t-1. Draft Daddy: This site is updated 3-4 times a day and has real, unbiased opinions. They don't claim to be know-it-alls or insiders, but they do their best to cover the draft. I check their blog every day for the latest draft news.
t-1. NFL Draft Countdown: Definitely the best rankings and scouting reports on the web. One of the most popular draft sites in the world.
3. Northwest Scouting: Probably the least fun part of scouting the draft: Linemen. Well, for most people. All that the Northwest Scouting site does is scout linemen, and like the people they cover, the site is nothing fancy. It just has the most in-depth linemen scouting reports on the web.
4. Consensus Draft: The most extensive player database on the web, this site also features a Post Your Own Mock Draft section, which is really a great idea. You can access most of their articles for free, but if you want to get even more, you can be a Premium member for $9.95.
5. Great Blue North Draft Report: Updated daily, the site is run by Canadians who know a lot about football. Their rankings lists have the most players on it that I've seen so far. One of their best features is an underclassmen scorecard, where you can find updated news on which way some undeclared underclassmen are leaning.