I replied to a post on other forum about this, but I think this forum is better for noting a wonderful tool for those of us who grade essays online. I've been using it for a couple of years. The tool is T.A. Toolbar, a shareware product that can be found at
Grading Essays is Better than Ever. I like it because I can grade an essay using a variety of buttons that insert comments automatically. It also has a holistic grading mechanism, plagiary detection, and can be customized to do whatever you need it to. Most of the comments it inserts into students' papers, by the way, have hyperlinks embedded in them, so if the student needs more information about a given error and how to fix it (such as comma splice or subject-verb agreement) they just click it and go. It's really quite brilliant.