Viewsonic, Samsung, and Sony all have widescreen LCD monitors out. They're given a 17" screen size, with native res of 1280x768 I think. Newegg.com has them for purchase. I'm pretty sure they all use the same panel, just each manufacturer packages it differently.
Samsung also makes a 24" widescreen LCD monitor; Sony makes a 23" widescreen LCD; a few other LCD manufacturers produce 22"+ widescreen LCDs (Iiyama, CTX, LG, maybe Eizo)....but they are ALL ridiculously expensive....at least $2000 in each case, and when you get into that range, video bandwidth starts to become a problem for DVI connections.
Sony also makes a 24" widescreen CRT, but it is massive in cost, energy use, weight, and size.
Personally, however, I'd rather get dual normal aspect ratio LCDs on a dual-head video card. For instance, two nice 17" LCDs (with very thin bezels, as NEC and Samsung have) would offer a 2560x1024 desktop, and would not cost much more than the higher cost of the widescreen LCDs due to the novelty of those special screens. However, don't let my personal opinion change your mind.