Y'know, I wish I could find someone to host that stuff for me ... arty html stuff just isn't my bag man!
The 'Learn how to write them' bit ... I never got around to finishing that. The bits that you want to look at currently are under the 'My DLLs ...' bit.
Pick out the Matrix1Utility (not the exe) from the top, and the Framework (3rd from the bottom) and download them. The framework is the one you should start with ... it's all commented and has a readme to help you. The utility one contains all sorts of commands so that you can see how I used to write DLLs.
Someday, I might get around to putting something together that explains how I currently write my DLLs ...