By its very nature, the jam band scene can overindulge in the repetition of motifs. It'd be easy to dismiss Keller Williams as a one-trick pony, too; the guitarist often performs cover-heavy solo sets as a one-man band, constructing songs live by looping guitar riffs and percussion. But Williams keeps things fresh by folding his studio experimentation into the concert experience. Over the last five years, his albums have spanned the guitar-free reggae/funk project Kdubalicious, a batch of kids tunes, collaborations with The Travelin' McCourys and The Keels, and discs devoted to bluegrass takes and solo piano covers of the Grateful Dead. — Spencer Griffith