I adore the nonsense poems of Edward Lear. He's most famous for The Owl and The Pussycat, but The Nutcracker and The Sugartongs is one of my favourites to read aloud: http://www.nonsenselit.org/Lear/ns/nutcrackers.html

When read aloud, the rhythm is impeccable and almost addictive.

Another shout out has to go to A A Milne, particularly for Disobedience, which again is a delight to read aloud: http://www.umiacs.umd.edu/~ridge/local/disobedience.html