A new LITA guide will be available in early February:

Lehman, Tom and Terry Nikkel. Making Library Web Sites Usable. Neal Schuman, 2008. ISBN 978-1-55570-620-3. 208 pp. $65.

From the LITA Blog:

With clear, non-technical language, Making Library Web Sites Usable breaks down what usability assessments are, why they are important for libraries, why libraries should do them regularly, and what the most common challenges are. They also explain all of the necessary how-tos, whats, and whys for the most common assessment techniques and how to interpret results, document findings, and effectively communicate results and recommendations.