I am a fan of ProFootballTalk.com (their rumor mill), but the best of the best of the best in my humble opinion is:
www.kffl.com/hotwKFFL's "Hot off the Wire" does not leave a bit of news out... and it is usually the first aggregate source to list news. PFT trails it by hours sometimes days. But it is all written in short teasers (which is great) just not as amusing as the editorializing on PFT which I really find entertaining.
Also... there's ProFootballWeekly.com's "The Way We Hear It". This usually has insider info other sites don't have, but it doesn't have a ton and it isn't updated as often as you'd want. They have great info on PFW though regarding FA's available at each position, draft stock, combine results, etc.
That's all I've got.