Best "one-on-one" recordings... one voice and...

Eva Cassidy - "Tall Trees In Georgia"
Greg Lake - "Lucky Man" and "Still You Turn Me On" from "Welcome Back My Friends To The Show That Never Ends"

I know this is an old post but I have been listening to Colin Haye for months and can't get it out of my head. He is the former singer from Men at Work in the 80's. I never cared for them then but this album is stuck on me. Just him and an acoustic guitar.

This is a slight cheat on the subject, but I find it an incredible recording:

Open Fire, Two Guitars - Johnny Mathis

http://www.amazon.com/Open-Fire-Guitars-Johnny-Mathis/dp/B00000JBDS/sr=1-11/qid=1161198269/ref=sr_1_11/104-3486952-3375107?ie=UTF8&s=music

Vincent Black Lightning - Richard Thompson