Stanford Scientists Put Free Text-Analysis Tool on the Web
That's pretty cool — I had the exact same goals (help professors grade essays faster) with my bookshrink project [0]. Of course, it was the first python code I ever wrote and it uses an extremely naïve algorithm, but the results aren't too bad if you want to try it yourself [1].[0]: https://github.com/peterldowns/bookshrink
[1]: http://www.bookshrink.com/