Throughout the course of her four studio albums, Norah Jones has honed in on a remarkably well-defined jazz-folk sound; even last year's relatively dark "The Fall" was instantly identifiable as the work of the woman who gave brunch spots everywhere the gift of a lifetime with "Don't Know Why." As a series of off-the-cuff side projects have shown, though, Jones' musical interests are more varied than they might appear, a fact that's demonstrated neatly on ". . . Featuring," which collects more than a dozen of her collaborations with a wide range of other acts, including Willie Nelson, Belle & Sebastian, OutKast and Foo Fighters. (There's also a song each by the Little Willies and El Madmo, two of Jones' side projects.) The singer is especially good on "Life Is Better," a sexy soul-rap track from Q-Tip's 2008 "The Renaissance," and on "Dear John," a bleary duet with Ryan Adams that reminds listeners that even multiplatinum prodigies can get the blues.