Some interesting GUI, Graphics, and OpenGL links:
GUI Toolkit Page
This web site provides a good jump site for a lot of GUI toolkits and it
is currently maintained where Platform Independent FAQ seems stale. It has
some wierd graphics and takes a long time to load into your browser page.
GTK
The Gimp Tool Kit. This toolkit is rapidly gaining acceptance for building
X Windows applications. It is an alternative for Athena and Motif widgets.
A V port to gtk is underway.
OpenGL
Official OpenGL home page.
Mesa
Mesa is a freeware version of OpenGL.
Interactive Computer Graphics
A good book about graphics programming using OpenGL.