The Sept. 1 issue of Library Journal addresses Evolutionary Biology in its Collection Development feature.
It includes older books that shouldn't be weeded such as Ronald A. Fisher's The Genetical Theory of Natural Selection and Julian S. Huxley's Evolution: The Modern Synthesis.
Some newer books they recommend include Encyclopedia of evolution, edited by Mark Pagel & published by Oxford; Richard Dawkin's The ancestor's tale : a pilgrimage to the dawn of evolution; Sean Carroll's Endless forms most beautiful : the new science of evo devo and the making of the animal kingdom; and Kenneth Miller's Finding Darwin's God : a scientist's search for common ground between God and evolution.
Also check out the web sites LJ reviews on the topic; they include:
* Darwin Digital Library of Evolution from the American Museum of Natural History
* Understanding Evolution from the Paleontology Museum at the University of California–Berkeley
* National Center for Science Education
If I were still at Hampshire, I'd be going on a buying spree!