Got 500k uniques daily.. What to do..?

Did you ever sort anything out with your traffic?

I will be happy to pay $3 per thousand popunders....

Adsense

Ok here is few things you can do:

1)Pop-ups at 1$/k visitor you can get like 500$/day
2)Nichee related CPA
3)Use incestives and create opt-in mail lists
4)Nichee related floating banners
5)Sell add-space
6)Re-position your Adsense ads for better click rate
7)If reviewing a nichee related book offer em a bonus when they exit
8)Offer other webmasters to create a post/article about their site and publish it on your site(of course they would need to pay)
9)Flip the site for big money
10)Nichee related Clickbank and Commison Junction products

Sell Banner Space , use google adsense and probably you can make a membership for your site , Hope this helps.

How about facebook clickjacking