Chris Whitley - Din of Ecstasy
I think that is my top underrated album. It is nice to see someone else feels the same way.
And the Booth and the Bad Angel album. For whatever reasons, it really worked for me despite not really liking James that much.
Oh, and Yusef Lateef's Live At Pep's, Hello Nasty, any Freddie and the Dreamers album, and DJ Shadow's The Outsider. I remember back in the day when Paul's Boutique was way underrated, now everyone has it.