boxesandarrows.com

Boxes and Arrows is one the best IA resources on the Web—a labor of love by IAs for IAs and remarkably prolific.

findability.org

Findability.org is a "selective, seriously incomplete, and perpetually evolving collection of links to people, software, organizations, and content related to findability." Despite its disclaimers, it offers a wide spectrum of links to topics, people and organizations. It's a great next step after gotoresources!

iawiki.net

The Iawiki is a collaborative discussion space and encyclopedia on information architecture. Read the instructions to learn how it works, then contribute, participate and benefit.

jjg.net/ia

The Information Architecture Resources of noted IA Jesse James Garrett is a must-visit. Great resources, lots of links, lots of great thinking.

info-arch.org/lists/sigia-l/index.php

The SIGIA-L mailing list focuses on all things IA—and probably a bit too closely as the discussion can get pretty nerdy. It will also fill up your inbox quickly. Explore its archives when you're looking for specific information.