Whew! Those links just pile up! Here's a bunch more to clean out my Opera links bar:

REST on Rails
styleboost.com
mollio.org - Nice HTML/CSS templates. I've got my own already, but very neat and GPLed.
Docking Boxes - More CSS goodness, cute little draggable boxes that you can manipulate with the keyboard.
typofile.com - A really great font hangout.
topographi.com - Another font meeting place online.
Fonts and Algorithms
More font info from Luc Devroye
TeX from Luc
Writing C extensions for Ruby - Extra neato!