We've released a jQuery lightweight rich text editor that is fully compatible with .NET applications.
Thank you to Batiste Bieler for the original script, jQuery Rich Text Editor Lightweight.
I heavily modified it to support ASP.NET forms (and their funny client IDs) and to work a bit more efficiently. It’s tested with PHP and .NET both. It should work with any kind of form.
Visit the jQuery Rich Text Editor project page for details.