OK, y'all have already mentioned many of my favorites,(esp Irving & Steinbeck) but nobody has mentioned Octavia E. Butler. Her trilogy that begins with "The Parable of the Sower" is not to be missed. Her books are classified as Science Fiction, but they are not overly Sci for those of you who are not really excited by Sci Fi.

For Kid Lit, I love the sadly out of print "A Tree for Peter" by Kate Seredy, "The Empty Barn" by De Angeli, and one I just previewed for my Jr High students, "Tangerine" by I'm not sure who.