The main income from the Site I'm geussing is Advertising...
To get good advertisers it depends on how many visitors use the site, and in some cases, how many people click the ads...
Also, taking into account the overheads for running the Site such as Hosting etc, who knows. I'd imagine it would be at least breaking even, otherwise the Site would ultimately have to close down...
Can honestly say that until reading this post I had never knowingly looked at the advertising on this site. I guess you get so used to seeing them on all sites I just block them out =)