I'd like to announce a selection of Web-based category theory demonstrations that I've put up at http://www.j-paine.org/cgi-bin/webcats/webcats.php . The page contains a number of buttons such as "generate and demonstrate an equaliser" and "generate and demonstrate a limit": clicking on one will generate an example of the construct in the category of finite sets, and display it as a listing of its objects and arrows, and as a diagram. For limits and colimits, the demos generate a small random graph, convert it to a diagram, then compute and display its limit or colimit. Comments would be very welcome. The demos are a bit of an experiment: I had some categorical algorithms lying around from other work, and thought it would be interesting to connect them to the Web. Jocelyn Paine http://www.j-paine.org/