Okay, I've been in this business long and have been through a whole lot of it really..
So here's the bottom line: internet advertising is bad right now, just horrible. A year ago a good CPM rate ($ per thousand hits) would've been $10 (Which is extremely good), nowadays a website is lucky to get $1 CPM. Meaning if your site gets 100,000 hits a month, you'll get $100. But a company like Flycast (if you get accepted) will likely pay nowadays $0.15-$0.20 CPM. If you're lucky it could go as high as $0.50. Good quality sites out there hover around $0.70 CPM.
There are two things affecting the CPM rate, volume and rates. It used to be that 80% of the inventory (which is based on hits, or possible impressions, as each hit can display a new ad) could easily be sold by big companies, nowadays it's more like 20%. When a pay ad isn't avaialable for pay, a "default" one shows up in its place. So with volume as well as rates decreasing, it leaves little room left to make any money at all.
I have much more knowledge to share about this subject, so if you have any questions feel free to ask. But the bottom line is, unless you plan to make the next Yahoo!, don't plan on relying in ads for any real amounts of money. Even Anand himself is having trouble selling his forum ad space, which is evident because the same "default" banner ads show up about 98% of the time from what I've seen..