I'm one of the 'old timers' over there because before I had my own forum back in 2000, that was pretty much the only place to go. So I guess I got "grandfathered" in.
I guess the big thing is that 99% of people that visit my website are looking for either flight training or pilot-type services, so I'm able to tell a potential advertiser that I've got a pretty tight demographic and the people they're looking for are right here.
Even though avweb.com, landings.com and various print media get 10-25 times the amount that I'm able to offer an ad for, I've probably got the tightest, most consistent demographic. I spy on other website's 'rate sheets' and man o man, mine are comparatively cheap, but it's always a challenge to convince an advertiser that they'll see a ROI quickly.
But most of the users at a.net are usually ones that like simply looking at airplanes which have little interest in flying or pursuing a career. Probably catering towards photography service companies or the flight simulator market would help him with his revenue model.