As if the online comedy sector wasn’t crowded enough already… Viacom’s (NYSE: VIA) MTVN Entertainment Group has relaunched Atom.com, combining the professional content of AtomFilms.com with the user-generated videos hosted by AtomUploads.com. MTV bought Atom two years ago.

With the launch, Atom.com becomes Comedy Central’s anchor brand for original digital comedy content, developing new properties for distribution and producing the half-hour TV series Atom TV that debuted on Comedy Central this week. The new brand offers community features such as a UGC upload system, user profiles, forums and the “Upload Showdown,” where users can vote for which UG video should be branded as one of Atom’s pro videos. Pro videos earn site promotion and a distribution and licensing contract with royalty payments via Atom’s rev sharing program. The site hosts channels featuring spoofs, sketch groups and cartoons, as well as original web series, Border Patrol, Stephen & Stephen, Stickman Exodus and Benny, Escaped Convict. Dozens more shows are currently in development. As for advertising, each video will include non-interruptive overlay ads and certain videos will use product integration.

It did a somewhat similar move with iFilm, which it bought and then merged it with Spike.com....it even launched a spinoff TV show on VH1 titled Web Junk 20, which was later canceled.