3D rotation about an arbitrary axis

I often need to do some geometric calculations involving rotation of a vector about an axis. However, not often enough to have the matrices for the rotation to hand. The calculation is not particulary difficult and is described in many places, but last time I needed this I found a very good write up by Glenn Murray:

http://inside.mines.edu/~gmurray/ArbitraryAxisRotation/

Not only is this an easy to follow description, it also has the final rotation matrices which makes it very easy to code.