How do you guys do your servers for those of you that have multiple sites...do you sign up for a site, and then put banner ads/popups on them to pay the cost, or what?
I own my own server, it costs me about $109 a month.
I get revenue from advertising and affiliate programs. I've made as much as around $3300 in one month with the average now sitting around $2500.
Traffic wise in total my sites generate roughly 1.5 million page views a month.
Are you trying to ask:
Do people with multiple sites get one ad contract for one site and then use those ads on all sites?
It depends. If you're a low volume, low bandwidth site then advertising make cover your costs. If you're high volume, need more than a basic dedicated server and need lots of bandwidth, advertising may not cover your costs.
To get contracts, you go to each ad network's sign up page and fill in the form. To get CPA deals, go to places like CJ, AffiliateFuel, Amazon, and sign up for their programs.