This category is made up of my professional secret stash of encyclopedias and overviews. While supplemented by frequent trips to the library, this group is still the backbone of the Archaeology website at About.com, and is guaranteed to help anyone get familiar with a broad bariety of topics.
1. The Oxford Companion to Archaeology
I absolutely rely on this book, and anybody who needs or wants a broad, general knowledge about world wide archaeology (with references to go find out more) should rush right out this instant and buy it. Packed with articles on everything from Acheulean Tradition to Zooarchaeology, with timelines and maps and a terrific index; edited by (who else?) Brian Fagan.
2. Archaeology of Ancient Mexico and Central America
Another wonderful, massive resource, concentrating on Latin America, and including articles on everything from Abaj Takalik to Zumpango del Rio; edited by Susan Toby Evans and David Webster. From Garland Publishing, and well worth every penny.3. Medieval Archaeology
Another spectacularly useful volume from Garland, edited by Pam Crabtree, containing articles on everything from Aggersborg to York.4. The Archaeology of Mainland Southeast Asia
This is probably the oldest text on my bookshelf right now, but I still find it useful as background for material on southeast Asia. Written by Charles Higham, and part of the wonderful Cambridge World Archaeology Series.5. Prehistoric Europe: An Illustrated History
From Oxford University Press and edited by Barry Cunliffe, an absolutely essential overview of Europe up until the Medieval Period.6. Prehistory of Australia
A strong overview of Australian archaeology, published by Smithsonian Institution and written by John Mulvaney and Johan Kamminga.7. Prehistory of the Indo-Malaysian Archipelago
I know this book by Peter Bellwood has been updated and improved; I'm currently using the 1986 version, but will upgrade soon. Another essential overview.