Flipcode was a place to discuss gamedev + algorithms with a unique flair and an outstanding audience, something IMHO gamedev.net never matched. I, too, was a regular visitor, poster, and also contributed the odd article and an IOTD. Terrain engines bordering on 100k polys without HW T&L will be forever in the past, but the spirit will live on.
(EDIT: This article is a more in-depth writeup of an algorithm that I developed around 2005, and first posted to Martin Baker’s Euclidean Space website. That time was the height of the Intel NetBurst architecture, which was notorious for its deep pipeline and high branch misprediction penalty. Hence the motivation to develop a branch-free matrix to quaternion conversion routine. What follows is the complete derivation and analysis of this idea.)
The original routine to convert a matrix to a quaternion was given by Ken Shoemake  and is very branchy. There is a way to eliminate these branches and arrive at a completely branch-free and highly parallelizable code. The trade off is the introduction of 3 additional square roots. Jump to the analysis section and the end of this article, or continue fist with the math bits.
I just got the news about the OpenGL 4.3 spec, which was released today, and is available at http://www.opengl.org/registry/. The spec document has been reorganized and cleared up considerably and is a lot easier to follow than the previous specifications. New features include (ordered by importance for my projects):
Queries for internal texture format parameters
Debug output callbacks
I’m currently on a project where compatibility and scaleability is prime, so the first two features are very welcome as development aids to make the code run robustly on a variety of platforms. Compute shaders and texture views are of course cool, but require the newest hardware, so they are lower in my list.