The first book on Beowulf cluster computing. Published in 1999, it is now quite dated. Both hardware and software have moved past the text. It does provide good coverage of the issues facing the cluster builder. (261 pages) ISBN 0-262-69218-X
How to Build a Beowulf by Thomas Sterling, John Salmon, Donald J. Becker and Daniel F. Savarese
http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=3898