CBS continues to invest in online properties as it looks to drill deeper into a space increasingly popular with its traditional advertising and viewer base.

The company ponied up $280 million for music-based social networking/Internet radio site, Last.fm. The site claims 15 million active users in 200 countires, many of them the younger audience that older-skewing CBS is looking to court.

CBS has also been raising its music profile, re-launching the

CBS Records

label with an online focus, hiring  a

music industry exec

to integrate more music in prime time, and even slating a new musical drama for the fall.

Founders Felix Miller, Martin Stiksel and Richard Jones will continue to run the site.

The move comes just a week after CBS bought financial news site

Wallstrip.com