If bestseller lists interest you, hunt down a copy of Michael Korda's extraordinary (and unfortunately, out-of-print) 2001 book, Making the List: A Cultural History of the American Bestseller, 1900-1999. You'd think our reading taste would change, but Korda's analysis will surprise you. They don't.
For example, compare the Publishers Weekly bestseller lists for hardcover fiction for the week of 3/21/11 with the week of 3/26/01 and you'll see more similarities than differences. We still like James Patterson and Maeve Binchy, and family dramas, intriguing mysteries, and historical sagas across generations never go out of style. Every author on the 2001 list continues to produce bestsellers today. The only noticeable difference is that we've cultivated a taste for fantasy (thank you, Stephanie Meyer). It's kind of reassuring to know that as much as how we read continues to change, the fundamental what we read stays pretty much the same.