I have made several contributions to Poplog.
The main one is the Popvision package, which may be found here at the Birmingham Poplog site. This includes material for teaching and doing research in Computer Vision, and also a multi-layer perceptron ("backprop") package. The whole popvision package is available in this tar-ball: http://www.cs.bham.ac.uk/research/poplog/popvision.tar.gz .
Here are some packages which may not have made it to the Birmingham site: