Here are a few references, in no particular order, to web pages of particular interested to network game programmers.

Game Networking API's

If you know of any other game networking API's on the web, please send their URL to dank@alumni.caltech.edu.

Online Game Networks

Note: many search engines list game networks. For example, www.itf.org has a good list.

Military-based Simulation Networking

Other sites of interest