This plugin adds an advanced code editor to the post content box on post.php and post-new.php. A third tab is added alongside Visual and HTML modes and you can toggle between the three.
NOTE: Visual Mode tends to eat up most/all of any special formatting. If you want to use ACE I’d suggest disabling Visual mode completely. You can do this easily yourself under Users -> Your Profile -> ‘Disable the visual editor when writing’. You can also do it for all users and for specific post types only. See the accompanying file no-visual.php for an example.
Not all features work in Internet Explorer v8 and earlier.
This does not work in full screen mode. Yet.
ACE Editor can do quite a bit more. If you have integration ideas, let me hear about it