Forum Moderators: skibum
If you are a website selling your own space you can get doubleclick to host your adverts, you can then get detailed stats from them regarding gegraphical breakdowns, clickthrough rates etc. You pay them a small amount per impression, something like .001 cent.
Most major companies who might want to advertise with you will either insist on doubleclick hosting or there are a couple of others, real media for one.
[edited]typo...[/edit]
The doubleclick website doesn't give anything away; (as I guess you've discovered) but if you're interested in acting as a publisher then start here:
http*//www.doubleclick.com/us/product/online/dfp/
Contact is only via enquiry - it's not a case of sign-up online and get the HTML....!
(delinked, sorry)