A U.S. federal court shuttered one of the world's top five adware and spyware suppliers at the request of the Federal Trade Commission (FTC), the government agency announced Thursday.

The move was the first FTC action that targeted a major player in the adware space.

Three California companies -- Enternet Media, Conspy & Co. Inc., and Networld One -- were shut down for allegedly using the lure of free music lyric files, browser upgrades, and ring tones to download adware and spyware on users' computers. Among the software surreptitiously installed on PCs were "EliteBar" and "EliteToolbar," two of the most widely-spread pieces of adware on the planet, according to Richard Stiennon, the director of threat research for Boulder, Colo.-based anti-spyware vendor Webroot.

"We've consistently found these in our top 10 of adware and spyware," said Stiennon. "They've been very effective at getting installed, sometimes even more effective than better-known adware."

The court also put a stop to the actions of an affiliate, the Ohio-based iwebtunes.com, from helping to spread the adware and spyware by offering blogs free background music. iwebtunes targeted Google's BlogSpot service in particular, offering bloggers Java code that would supposedly add free background tunes to their blogs. In actuality, the code popped up bogus dialog boxes on the screens of those who viewed the contaminated blogs; the dialog boxes claimed that the PC was a security risk, and offered to update the browser and/or deliver security software.

Among the specifics in the