Classes of numbers I've done work on include

Paul Zimmermann is running ECMNET which is another distributed factoring project. It uses Lenstra's Elliptic Curve Method to find relatively small (up to 55 digits or so) factors of integers. Many people run the programs "by hand". For those who prefer an easier life, Tim Charron wrote a client/server harness to ECMNET so that the computation may proceed without human intervention. I am running two ECMNET servers on the IP address That which is running on port 8194 is currently loaded up with the (Generalized) Cullen and Woodall numbers, whereas that on port 8195 is loaded with the Homogeneous Cunninghams.