The Newbery Medal was awarded to children's books looong before I started reading...but somehow I missed a number of Newbery Medal-winning books. How does that happen? No matter. I plan to read them ALL (and in the case of several winners, the rest of the series as well).
2004 Medal winner: The Tale of Despereaux: Being the Tale of a Mouse, a Princess, Some Soup, and a Spool of Thread by Kate DiCamillo
1996 Medal winner: The Midwife's Apprentice by Karen Cushman
1984 Medal winner: Dear Mr. Henshaw by Beverly Cleary
1980 Medal winner: A Gathering of Days by Joan W. Blos
1979 Medal winner: The Westing Game by Ellen Raskin
1968 Medal winner: From the Mixed-up Files of Mrs. Basil E. Frankweiler by E.L. Konigsburg
1966 Medal winner: I, Juan de Pareja by Elizabeth Borton de Trevino
1953 Medal winner: Secret of the Andes by Ann Nolan Clark
1942 Medal winner: The Matchlock Gun by Walter Edmonds
1936 Medal winner: Caddie Woodlawn by Carol Ryrie Brink
1923 Medal winner: The Voyages of Dr. Dolittle by Hugh Lofting (no blog post due to flood of 2008 but I will briefly mention that the jingoistic, racist, and misogynistic tone was a bit much)
1922 Medal winner: The Story of Mankind by Hendrik Willem van Loon (posts here, here, here, and here)