Does anybody know where I can find out how much to charge for a banner ad based on the number of hits?
Right now one of my sites gets 500 hits a month. That's not much but how do I find out how much I could charge with that?

If I knew how much I could charge for 10,000 hits a month I'd put more effort into beefing up the content.

Well I've found this http://www.ecommerce-digest.com/persuasive-advertising.html which seems to be informative.
They suggest charging around $20 per 1000 page views. They also suggest hiring a company to set up the advertising for you and then letting them get paid off commission.