Why are green-eyeshades types calling AdBrite's customers and asking probing questions about the online-advertising network? The company founded by Philip Kaplan of FuckedCompany fame — pictured here with some friends — might be giving accountants an eyeful for a host of reasons. Let's rule out an IPO: The Sequoia Capital-backed startup, with a rumored $40 million in gross revenues, is still too small to go public. That leaves an acquisition as the most likely scenario. Yahoo, Google, and Microsoft have all bought ad marketplaces recently. But for Barry Diller's IAC, which also owns second-tier search engine Ask.com, AdBrite would be a modest purchase. One other possibility: AdBrite could be making a buy of its own to get more heft. Anyone heard more?