With 1.5 million copies of Heavier Things sold since September, there probably aren't too many John Mayer fans who don't own a copy of his latest album. But they may want to splurge for another next month to get a new five-song bonus disc that'll be given away with it.

When people purchase Heavier Things at participating retailers, they'll be handed the bonus disc, which features two recordings of Mayer's current single, "Clarity" (an acoustic take and a radio edit), live versions of "Come Back to Bed" and "Neon," and a track that's been a component of Mayer's live show for a few years.

" 'Kid A' is this little funny thing that happened while we were making [2001's] Room for Squares," Mayer explained of his Radiohead cover. "John Alagia, who was producing the record, had to go away for the weekend. So myself and Jeff Juliano, the engineer, just started messing around. I tooled up this version of 'Kid A' because I love the song, I really do. And within an hour and a half or two hours, it was all done."

Where Radiohead's version of the title track from their 2000 album is an amalgam of looped beats and electronic tones, Mayer rendered his take acoustically, demonstrating his versatility and dexterity as a guitar player. Another fundamental difference is that on Mayer's track, the lyrics can actually be understood.

"The thing about doing covers, for me, is that I don't really feel like I can cover just any song," he said. "I can't particularly sing somebody's notes clearer or higher or stronger, which is why it was such a cool thing to cover this song. There's a tune there, but it was almost purposefully obscured, like a robot was singing it. It was one of the few songs I could do something with -- if you're gonna do a cover, leave the song somewhere different than where you picked it up."

Mayer continues his exhaustive American tour in support of Heavier Things through the end of this month, when he'll collaborate with country star Brad Paisley for a taping of CMT's "Crossroads." He'll then tour New Zealand and Australia until April 22. After that, Mayer said he may play a show or two with Sting, whom he described as "the musical Jedi."

"Sting is such a cool guy that, as long as it was with Sting, you could do anything in the world and tell all your friends about it the next day over a pitcher of beer [and they'd think it was cool]," Mayer said, before serving up an imaginary scenario: " 'Sting and I were driving up the coast of California ... next thing you know, we stop off at a rest stop and we're [getting naked] in one of the stalls ...' " He laughs, then continues, "And all your friends will be like, 'Yeeeahh!' Why? 'Cuz it was Sting."

Mayer joined Dave Matthews, Elton John, Elvis Costello, Mary J. Blige, Kylie Minogue and others in paying musical tribute to the former Police frontman at last month's MusiCares Person of the Year ceremony in Culver City, California, where Sting was honored. Mayer said a musical collaboration is not out of the question, though he noted that Sting would have to do the asking.

"It's like inviting yourself over to your friend's house for dinner," he said. "You just don't do that."