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.

Features:Download the Last.fm software, and it builds your music profile based on the iTunes tracks you listen to. Your profile page hosts your radio station (songs already in your collection), recommendations and friends' lists, as well as tracking your top artists and upcoming concerts you are attending. Artists with videos include Feist, Rilo Kiley and Kylie Minogue. A new program pays artists royalties for streams.

Comments:"Last.fm is great at helping you to discover new music and meet like-minded fans," Resnikoff says. "By monitoring everything you listen to, including on iTunes and iPod, Last.fm creates a profile of your tastes. (It) also allows you to stream new music you might like."

Mog.com

Description:Used by 1 million "Moggers" monthly, this network connects you with others who have similar tastes and lets you share discoveries.

Features:Visitors can scan the community's blogs (or Mogs) for reviews, top songs and videos. Some songs require a Rhapsody music-service membership to be streamed in their entirety. Download the Mog-O-Matic program, and it will scan your music library and create "a musical representation of you," says Mog creator David Hyman. At the recent South by Southwest Festival, Lollapalooza creator Perry Farrell interviewed Lou Reed for the site.

Comments:Mog.com "solicits input, like reviews and artist write-ups, from members," Resnikoff says. "The result is a user-generated community of fans that can be targeted to the genre tastes of the subscriber."

Pandora.com

Description:Part Internet radio, part recommendation engine, Pandora automatically adjusts a playlist to your tastes based on the tracks you indicate you like or dislike. Pandora has more than 11 million users.

Features:You can forward your "station" to friends and find others stations based on genre, style, mood and listener profile. Become enamored with a new song, and you can create a station around it, bookmark it or click to buy from iTunes or Amazon.com. You also can listen to Pandora on AT&T and Sprint cellphones.

Comments:"Pandora crafts highly targeted radio stations based on your preferences," Resnikoff says. "You actively tell Pandora if you like the music they are serving you, and that becomes the basis for your customized station. It's less geared toward networking, though you can link with like-minded listeners."