Jitbit Software. Initially used internally for our software products -
web help desk and ASP.NET Forum, but then we decided to go public and share this with the community.
It works like any web-based WYSIWYG editor, but it inputs and outputs
BBCode instead of HTML.
It's free and open-source (BSDlicense), use it for both free and commercial projects. Please leave a note in "discussions" if you want to contribute.
PS. Instead of downloading it is highly recommended getting the latest source codes, all the hottest fixes are there.
Check the screenshot: