Former physicist by training, so I used to do a lot of stuff with matrix decomposition, and things such as least-squares solvers.. Nowadays I write a lot of template-based vector math routines (hence the interest in Eigen), but I figure if I want to contribute it might be best if I just go on a bit of a deeper tour of Eigen than present and see how some of the bits I've not looked into yet work, and if they aren't documented or have TODO:doc by them maybe write a few comments - are you interested in doc patches to start with?
Gareth