I'd say yes, definitely, though I'm hardly an expert and the only others I've read are The Crying of Lot 49 and Mason & Dixon (both of which are also excellent).
Faulkner, Woolf, and Beckett are some of my favorites ever! I still think that Woolf's The Waves is the best thing ever written. My top five (not including that or GR, as they've already been mentioned): The Sound and the Fury (Faulkner), Pale Fire, Lolita (both Nabokov), To the Lighthouse (Woolf), Ulysses (Joyce). Those aren't really postmodern, though (wait, that's a lie, Pale Fire is); for that I'd suggest stuff by Paul Auster, Julio Cortázar, Donald Barthelme. If Danielewski's House of Leaves counts (does it? to be honest, I'm not entirely certain where the boundaries lie), then definitely definitely that.
Oh man, I could go on.