Nineteen million people use Last.fm through off-site widgets and third-party hacks, the company says (via release). That’s almost as many as the entire 21 million on-site monthly user base from the site itself - a big recommendation to those worried about off-site syndication. But then, Last.fm’s ads are visual, not audible, so that’s 19 million users who aren’t generating much cash. The site unveiled a widget showcase today and plans to open more of itself to third-party developers this year.

After its acquisition by CBS (NYSE: CBS) last year, it’s now playing heavily for the American market, too - a press release trumpeting recent US growth last week, and a high-profile panel appearance in Manhattan for all three founders tonight.