IOSA.it looks worth bookmarking:
IOSA stands for Internet and Open Source in Archaeology. It is a research group of young archaeologists, and the aim of this site and of IOSA research team is to promote the use of open source software and open stardards in archaeological computing. We hope you can help us making it a good place to come for all who are interested in archaeology and free software (free as in freedom).
As Peter Suber notes, among the many useful links there is MapTools.org, “a resource for users and developers in the open source mapping community, and a home to many open source projects.”