Praising iTunes is like endorsing chocolate and puppies: well, duh. Even so, any discussion of music on the Web has to start here. With its supersize catalog (more than 2 million tracks), fair pricing, and any-idiot-can-figure-it-out interface, it's most people's first stop for downloading the latest Kelly Clarkson single or Mariah Carey remix. Since it launched in 2003, iTunes has trounced its competitors, capturing close to 75 percent of the marketplace and selling more than a billion tracks.
But while everyone knows iTunes is big, fewer people realize how useful it can be for finding new tunes. Start with its top 100 downloads updated daily and you'll see an instant, direct reflection of American musical tastes: the newest Dixie Chicks single; surprise emo phenoms Panic! At the Disco; that Daniel Powter song that's on American Idol every week. Then move on to the ''essentials'' playlists, full of offbeat cult favorites. (Thanks to the ''Folk 101 Essentials,'' John Prine's epic ''Angel From Montgomery'' is our new after-work beer-sipping soundtrack.) And one of iTunes' best features is actually free: The site has grown into a portal for thousands of Web radio stations and eccentric podcasts, offering everything from rowdy dancehall reggae to classical music. Happy hunting.
GREAT FIND RJD2 & Ric Ocasek's ''Through the Walls''
This underappreciated, expertly curated MP3 store is the music geek's alternative to iTunes. It's packed with fantastic choices, and at $9.99 a month for 40 downloads, it's a great deal. Emusic sells tunes only from independent labels, which means you won't find most current pop hits here. But spend some time sifting through its 1.2 million tracks including new stuff from Neko Case and Spoon and classics by Johnny Cash and Otis Redding and you won't care. Best of all, the site's sharp editorial team steers you toward the good stuff with articles on the best Parisian jazz or the latest Brazilian pop. And their ''Dozens'' lists are essential 12-album starting points in categories like ''boomer-friendly rock,'' or ''English folk,'' or ''old-school punk.''
GREAT FIND Art Brut's Bang Bang Rock & Roll
Perfect for anyone who likes surprises, Pandora is a wizardly website that lets you customize a radio station to fit your own tastes. After logging in, users type in the name of a song or a band (the Beatles, for example); then Pandora uses a complex mathematical algorithm to find tracks matching the Liverpool lads' musical characteristics. In addition to Fab Four songs, our station came up with some Kinks and Stones, lots of obscure '60s nuggets, and unexpected contemporary acts like the Pernice Brothers.
GREAT FIND The Move's ''Curly''
If other MP3 stores leave you hungry, tuck into this musical buffet. Pop gluttons will love Rhapsody's all-you-can-eat subscription service, which lets you download as many songs as you like for $9.99 a month. (Though the tracks will vanish from your hard drive when you stop paying. And it won't work with an iPod.) Another draw is the playlists, the most creative and well thought-out of any MP3 store. Their genre mixes go way beyond the obvious into left-field genres like ''pub-rock explosion'' and '''80s paisley underground.'' And somebody on staff obviously has a sense of humor: ''Yacht rock'' features smooth-sailing soft pop (Kenny Loggins, Michael McDonald) fit for a day of sipping Cape Codders down at the marina.
GREAT FIND Firefall's ''Just Remember I Love You''
There's a lot to dislike about MySpace. It's uglier than a Commodore 64, the music tracks are slow to load, and it has been co-opted by record labels, which pay for prime placement. Still, with more than 1.8 million bands offering their own homepages, it's impossible to ignore it seems like every act you've ever heard of (and countless unsigned acts you haven't) posts free songs here. Read about a band? Head to MySpace and you're basically guaranteed to get something for your time: a prerelease album preview, a new single, or even a raw demo. Weezer and Nine Inch Nails debuted their latest albums here, and Fred Durst recently posted a rant about former Limp Bizkit guitarist Wes Borland. Maybe that's not a compelling advertisement, but hey, there are at least 999,999 non-Durst bands on there, too.
GREAT FIND Love Is All's ''Talk Talk Talk Talk''