Using Josh's meta mod, I added different meta tags, descriptions, titles, etc. for each seperate forum I had. This made the ads more specific to the content.
I'm currently making about 30 dollars per day from google adsense on 2500 unique visitors per day, and that is on one tall add on the right sidebar only. Soon, I'll be adding it to the other 8 sites that use my nursing forums and hopefully, can get that up to over 150 dollars per day.
This is in addition to my paid banner ads, and I only added it at the urging of another site owner who was doing so well. I'm glad I did!