I can't add too much about his importance to fiction in general than the various obits that are appearing as I write, but I can say that for a quite a few years, David Foster Wallace's writing was a guiding presence in my life. Infinite Jest was a beautiful, sprawling mess, but one that got me through my year of thesis writing (e.g. it took me almost half of that year to plow through it), and taught me things about Boston that simply living in Cambridge wouldn't ever achieve (and taught me the fun of the egregious footnote). A Supposedly Fun Thing I'll Never Do Again, among other things, consolidated a lingering fascination with pro tennis that IJ seeded, and made consider the abstract beauty and physical elegance of the sport (and I've still never taken a cruise). Everything and More was a manic trip through the life and work of Georg Cantor that, despite it's verve and love of the subject and vain hope to explain it to the literate masses, made me question the very existence of editors in the publishing industry. And Consider the Lobster made me do just that, although the drastically abridged audiobook iTunes sold me, that got me through quite a few rides back and forth to BNL, made me deconsider it just enough to eat them again.
Needless to say, I'm crushed by his passing. WTF, DFW?