I'm thinking something along the lines of [TinyMCE][1]

Please include a list of features.

Examples include:

 - supports text formatting
 - supports links
 - supports images
 - syntax types (markdown/wiki/etc)
 - licensing and/or pricing
 - customizibility
 - plugin support
 - browser compatibility

*Note: Please limit the answers to one editor per answer to preserve cleanliness*

**Update: Forgot to add browser compatibility to the list**

  [1]: http://tinymce.moxiecode.com/