Tune in, turn on to music

— -- The millions of users of music-focused social networking websites have caught the attention of artists and labels. "With so many people spending such longsessions on the (sites), the bands want to get in front of you," says Paul Resnikoff, editor of DigitalMusicNews.com. USA TODAY's

Mike Snider

offers a playlist of tuneful social sites:

iLike.com

Description:The social music discovery site with 23 million users recommends songs and artists and lets you connect with fans of bands. You can stream songs and get free new-artist MP3s.

Features:iLike can be added to your Facebook profile, and the iLike Sidebar desktop plug-in displays concert alerts, bulletins and related artists as you listen to music on iTunes and Windows Media Player. Artist interactions in addition to R.E.M.'s listening party include U2, the Eagles and Radiohead official videos.

Comments:"Lots and lots of band profiles within a social network you use, whether it's Facebook, (other compatible social networks), Bebo, hi5 or another network," Resnikoff says. "You can easily link up with like-minded fans, and bands can use iLike to gain better distribution online."

Imeem.com

Description:An online community of 20 million monthly users that labels itself "the new social mixtape."

Features:In addition to user-generated playlists of full songs, several playlists are from artists such as Sheryl Crow and Tift Merritt who talk about tunes they have written or songs that touch them. You can post a blog, videos and photo albums. Videos from Flo Rida, Danity Kane and Day 26 can be shared and embedded on personal sites. When you find songs you like, one click lets you buy them from iTunes or Amazon.com.

Comments:"This social network is multimedia-focused and allows you to share streams with friends and layer music into your profile," Resnikoff says. "They have content from all major recording labels."

Last.fm

Description:A streaming music and recommendation service with 21 million unique users a month.