w3schools - A nice site with tutorials and references.
htmldog - Another site with tutorials and references. (Shared by Hayden.)
wifeo - This has a bunch of cool examples of things you can do in CSS labeled by difficulty.
csszengarden - A collection of cool CSS designs. (Shared by Camille.)
3D Worlds with HTML and CSS - (Shared by Sean M.)
Insane Interactive Resume - To understand how insane, play with the scroll bar. (Shared by Sean M.)
Web Jargon - (Shared by Zach S.)
Chrome Extensions - (Shared by Zach S.)
Startup Ideas - These are potential startups from 2008. They would make good project ideas for the class.
Just Pages
Meetups
Hill Country JavaScript - Group of JavaScript programmers
Ruby Rebels - Group for Ruby on Rails