RealMint is an ANSI terminal emulator and telnet client written completely in JavaScript. When installed, RealMint lets you login to your server from a web browser using telnet and an encrypted HTTPS tunnel.
ajaxWM is a themable ajax-and-python-based window manager, which provides multiple flexible terminals in a web-browser for comfortable remote-controlling of a computer via a network without having to install any software on the client-side.
h3270 is a program that allows you to use IBM 3270 hosts from within a web browser. It is different from other, similar systems because of its highly configurable layout engine that is based on regular expressions.
etcWebClient is a Unix/Linux server application that allows users to connect to the server from a browser. The web-based application includes an Editor, filesystem Treeview, and Console (etc).