Well, it comes out a bit more than quarterly, and it's not so much Underground as a compilation of generally available texts, but otherwise, it's a pretty nice job. Written in the Wired Magazine style, that is, very intelligent, very thorough, but somehow lacking in real meat, this Journal covers all sorts of aspects of the world of Computers, which might theoretically be of interest to those in the "Underground", whatever that is. All in all, solid but not awe-inspiring. Every single issue tries to sell you Legion of Doom T-Shirts.
The Journal of American Underground Computing Issue #1, March 19, 1994
The Journal of American Underground Computing Issue #2, April 4, 1994
The Journal of American Underground Computing Issue #3, April 30, 1994
The Journal of American Underground Computing Issue #4, June 7, 1994
The Journal of American Underground Computing Issue #5, August 1, 1994
The Journal of American Underground Computing Issue #6, October 1, 1994
The Journal of American Underground Computing Issue #7, January 17, 1995
Introduction to The Journal Of American Underground Computing