Short description
Since this is often used in technical writings, a button with which the selected text can be formatted in monospace would be very useful.
Fortunately, this was already present before, and just needs to be re-enabled in moinfckconfig.js:
1 --- moin-1.6.070814-unpatched/share/moin/htdocs/applets/moinfckconfig.js 2007-08-14 01:44:13.000000000 +0200
2 +++ htdocs/applets/moinfckconfig.js 2007-08-20 16:05:38.000000000 +0200
3 @@ -35,7 +35,7 @@
4 ['MoinFormat'],
5 // disabled some styles until IE endless loop is fixed:
6 // ['Bold', 'Italic', 'Typewriter', 'Underline', 'StrikeThrough', '-', 'Big', 'Small', 'Superscript', 'Subscript'],
7 - ['Bold', 'Italic', 'Underline', 'StrikeThrough', 'RemoveFormat'],
8 + ['Bold', 'Italic', 'Typewriter', 'Underline', 'StrikeThrough', 'RemoveFormat'],
9 ['OrderedList','UnorderedList','-','Indent','Outdent'],
10 ['Link','Unlink','Attachment','Image','Smiley'],
11 ['Table','Rule','SpecialChar'],
moin-enable-typewriter-in-gui-editor.diff
Notice: It might be necessary to clear the browser cache before this change will take effect, Shift+Reload did not work for me (Firefox 2).
Additionally, it is necessary to add an image for the new button to htdocs/applets/FCKeditor/skins/silver/toolbar, for example this one: 
Discussion
Alternatively, add it to the "Format" drop-down? There is already a Formatted option that creates <pre> blocks (and should probably be called "pre-formatted". Is that list configurable? I guess if FCKeditor already had the other method built-in, that's probably easier. -- SteveDavison 2007-08-20 18:44:55
I believe the drop-down is for formatting which applies to a whole line (or block), whereas the buttons right to it are for formatting which is inside of a line/block. At least there are only block-level formatting options in the dropdown right now -- ChrisVigelius 2007-08-20 21:39:00