SAN FRANCISCO — Dalton Caldwell graduated from Stanford with the same ambition as many Stanford students: to create a popular Web site.

It worked for Google's founders, and it clicked for Caldwell as well. Imeem, his social media site, attracts 20 million users every month. Each day, 65,000 new people visit the site, which Caldwell, 27, founded in 2003.

Imeem is like Facebook or MySpace in that members are encouraged to create personal pages with information about themselves. But since it is a social media site, these pages are focused on artists and albums, with personally created playlists featuring either single- or multiartist mixes.

Creating playlists is easy. You type in the name of an artist or a song, and a page pops up with related media — individual songs, playlists created by others, even photos or animations created by other members. Click the "playlist" tab, name your playlist and a song or video has just been added to the mix.

The site's success is "a little overwhelming," Caldwell says during an interview at Imeem's offices. "But it just goes to show the power of technology. People spend so much time complaining about things — it's kind of amazing what our little company was able to do. People can go to Imeem.com and listen to free music and be a part of a community, and it's completely legal. Real change happened, and it's great that we were a part of that."

Caldwell's original goal was to create a community site that focused on media instead of jobs or dating, which were popular at the time.

"We started with blogging and photo-sharing and that helped us build a community," he says. "We added music playlists as a great way to express yourself. When we came up with that, it took off faster than I ever could have imagined."

Dalton and Chief Marketing Officer Steve Jang went to work on the music labels to persuade them to offer ad-supported, on-demand music for free — something no label had ever agreed to. Warner was first. A year and a half later, in December 2007, the last holdout — Universal — signed on. Imeem splits ad revenue with the labels.

Besides music, Imeem offers videos, photos, music and TV shows. It recently cut a deal with MTV Networks to show clips from MTV, VH1 and Comedy Central.

The name Imeem was inspired by sci-fi author Richard Dawkins, who coined "memes" in his 1976 book, "The Selfish Gene." "Memes are the basic units of a culture," says Caldwell.

"We thought it was a great name for the site and something that got across the message that we were a site for people to express themselves and spread the culture."