The Friend of a Friend (FOAF) project is creating a Web of machine-readable pages describing people, the links between them and the things they create and do.
Description of Conkeror, an extension for Firefox which allows controlling the browser with (mostly Emacs-like) keys instead of mouse clicks.
On 2021-10-12, the site was off-line and the http://conkeror.org extension is probably obsolete.
YouOS is a web operating system that lets you run diverse applications within a web browser. Small applications like sticky notes or clocks. Large applications like word processing, mp3 players, and instant messaging. Even better, it's very easy to tweak
PHP Shell is a shell wrapped in a PHP script. Its a tool you can use to execute arbitrary shell-commands or browse the filesystem on your remote webserver. This replaces, to a degree, a normal telnet connection, and to a lesser degree a SSH connection.
This is a collection of information (mostly links) about (Common) Lisp, using a system written in CL. While I am far from understanding it, I think that valuable ideas can be found here.
ASCIIMathML allows to write formula in a (La)TeX-like format and have it rendered decently on modern browsers (some math fonts are needed). The blog is quite interesting as well.
S5 is a slide show format based entirely on XHTML, CSS, and JavaScript. With one file, you can run a complete slide show and have a printer-friendly version as well.