Crappy thing is, you can't even get ranked lists out of Compete even at the "pro" level which is like $500 a month. But, you can get it out of quantcast for free.
If you go to the media planner (you have to register for a free account), go to filters > category and select what you want (e.g. politics & commentary), then choose the radio button that says "filter sites strictly", then go to min us reach, choose '500', after it loads sort by US people...and there you have it...a ranked list of alll the sites in that niche by traffic. You should be able to download into a CSV, but it looks like that's broken right now. Hit me on AIM if you have any other questions.
Speaking of which, I have a pro account for about another week and my account is about to cancel. I have a bunch of credits left, so if there are any referral reports or anything you guys need, pm me and I'll do what I can to accommodate.
PS> This is only for people who are actually part of the WF community, so if you're a noob, don't even bother asking.