Plant's most recent album, Band of Joy, is the best solo work he's done. I enjoy this one as much as his best Zeppelin work.
A few years ago I thought Robert was washed up -- he was on one of the late night talk shows (maybe Jimmy Kimmel, or Conan), he was singing something, and I'm thinking, it's over Robert. Then he did that great duet album with Alison Krause and now Band of Joy -- I understand why he turned down the Zeppelin reunion tour.