Richtextinput is a project mainly written in JAVASCRIPT and SHELL, it's free.
A javascript-enhanced input element with support for rich text formatting
Rich Text Input is a Javascript-enhanced input box with support for rich text formatting. It makes it possible for text inputs to provide unobtrusive, instant feedback about how the user's input will be interpreted.
Current release: 0.2 (dev snapshot, works pretty well in WebKit, Gecko, and IE).