DD-B's suggestions are good. I might add Andre Norton, esp. The Zero Stone and The Time Traders. Half Magic by Edward Eager remains my second favorite fantasy (after LotR). Jane Yolen's Briar Rose is a retelling of the Sleeping Beauty story set against the Holocaust, and Kara Dalkey's The Nightengale, while not precisely juvenile, is a retelling of the classic Japanese fairy tale.

While I can't speak to the tastes of today's 8-year-old daughters, books I enjoyed at roughly that time (or just after) in my life (hmmm... second grade?) included Black and Blue Magic by Zilpha Keately Snyder, The Little House on the Prairie books, The Story of Dr. Dolittle; (I eventually read almost all of them, with, iirc my favorite being the second, The Voyages of Dr. Dolittle).

At the moment, I'm probably better recommending kid's music to her (or trading mix CDs...).

Maybe I should ask my niece.