I've been marking assignments online since last century and quickly worked out that Word's revision tracking, and comments and autotext were a good first step to saving time when using reusable comment banks. But it is not easy to move the comment banks to another computer and some people find using autotext (Word 2003)or quickparts (Word 2007) to be too big a hurdle.
I ended up creating an addin called eMarking Assistant which works using floating toolbars in Word 2003 or 2007. It allows teachers to use predefined comments which can contain text, links, images and audio and or enter new comments (including audio) and save them for reuse. Below is a screen movie with section headings and explanatory text.
http://www.baker-evans.com/emarking-assistant/movies/using/
A 30 day trial is available for download and site site licenses are available.
I also surveyed the other online marking tools that are available and a list with their promotional materials is available at http://www.baker-evans.com/community/mod/forum/view.php?id=306
Feel free to add other tools to the list.
Peter Evans