I would say Neutral Milk Hotel, ELliot Smith, Leonard Cohen, Nick Drake, Bright Eyes-the usual. How about you?

"Living with Ghosts" - Patty Griffin & "Live at Massey Hall 1971" - Neil Young are two of my favourites.
Kristin Sweetland & Jenn Grant are a couple of wonderful new names in acoustic music.
Some great vetrans who are still at it include Greg Brown, Eliza Gilkyson & Bert Jansch.

NMH, the Decemberists, the Nirvana Unplugged.

There is a thread strikingly similar to this one. Some of the bands and artists mentioned here have already been mentioned over there. I will leave it up to see where it goes, if it ends up being repetitive or there is very little participation, I will close it.

Bill Withers released some great acoustic soul records. Donny Hathaway's best stuff was acoustic.

Michael Murphy's mostly acoustic Blue Sky Night Thunder was always a favorite of mine.

Leadbelly, Big Bill Broonzy, Robert Lockwood, Jr., Taj Mahal and a shitload of other blues artists deserve to be mentioned. As well as all the great unplugged folk music artists from the past (Anne Briggs, Judee Sill, Davy Graham, Incredible String Band, Maddy Prior, early Dylan, etc).

Hey, crazed, your mentioning unplugged immediately gets me to think of Nirvana's MTV Unplugged in New York (even if kendo beat me )

And, once seen, who can forget Richie Havens at Woodstock?