I took one of his earlier essays, one that was to my knowledge previously unavailable to anyone without access to a good library, and scanned/typeset it into a nice PDF. You can read it:
Fictional Futures and the Conspicuously Young (LaTeX source).
A friend scanned an interview with DFW by Dave Eggers. It comes from Issue 8 of The Believer, which dates it in late 2003.
Topics discussed include his writing process, political writing, chewing tobacco, pop-math books, teaching, etc.
Best American Essays
DFW wrote the foreword. I re-typeset it.
Best American Essays 2007 Foreword.