The band’s first three albums have been remastered from the original audio tapes. As with last year’s remastered Joshua Tree, guitarist Edge oversaw the latest remastering of U2’s catalog material.

Working with Universal Music Enterprises, the deluxe versions of the band’s classic first three efforts also contain bonus material, including b-sides, live tracks and rare finds.

Among the extras on Boy, fans will find a previously unreleased mix of “I Will Follow” as well as a previously unreleased “Speed Of Life” and a live version of “Cartoon World” recorded in Dublin at National Stadium.

On October the goodies include live versions of “Gloria,” “I Fall Down,” “I Threw A Brick Through A Window,” “Fire” and “October” recorded at London’s Hammersmith Palais. Other extras include remixes, Richard Skinner BBC Session material and concert recordings made in the United States and Netherlands.

Among the extras on War are unreleased tracks such as “Angels Too Tied To The Ground,” a club version of “Two Hearts Beat As One” and a Common Ground remix of “Tomorrow.”

Streaming the first three U2 albums is the latest high-profile project for imeem, which has already scored considerable success this year debuting albums and videos by Radiohead, New Order, The Rolling Stones, Avril Lavigne and Ray J.

The U2 / imeem hookup is yet another example of bands and labels harnessing the promotional power of the Web. By streaming the albums, Universal and U2 are not only creating an awareness that the band’s older material has been remastered, but are also making it extremely easy to listen and buy.

For example, in addition to streaming the albums, imeem is encouraging fans to embed the streams in their own blogs and social-networking pages, thus increasing awareness of the remastered albums. Of course, embedded streams make purchasing the CDs from imeem as easy as a mouse click.

Then there’s the advantage of presenting the band’s first three albums to a generation of music fans that weren’t around when the titles were first released. Not only will U2 and Universal sell the remastered CDs to longtime fans, they might pick up a sizeable new audience as well, thus enlarging the total fan base for years to come. That’s not a bad result for letting people listen for free.