Now that Twitter is almost a publicly traded company, it's under pressure to find meaningful new sources of revenue. That may include advertising outside of users' social streams, according to a new report from the Financial Times. Its sources claim that Twitter is developing an ad network for apps and websites that would target visitors based on what users tweet and who they follow. It wouldn't resemble Facebook's login-based advertising, however, as much of Twitter's data is public. The network would reportedly launch soon after the firm completes its recent acquisition of MoPub, a mobile ad exchange. Twitter isn't commenting on the rumor, but such a move is logical -- it would let the company improve its bottom line without intruding any further into our conversations.