Here is the periodic sampling from my del.icio.us favorites list. This time I chose the tag "WebConferencing."
Getting Started with Web Conferencing: Things to know when choosing a web conference tool.
28 Web Conference Training Tips: From E-Learning Weekly, this article offers some helpful tips specifically targeted to web conference training.
Dimdim: A free web conferencing tool.
Yugma: Another free web conferencing tool.
Cool Conference Live: Yet another free web conferencing tool.
Web Conferencing Services: A comparative table posted in late 2008 that compares a number of web conferencing tools, using metrics such as pricing tools, # of users, local/hosted, video, etc.