Ginger -Grammar Checking-Proofreading Software
Ginger Software is an excellent grammar and proofreading application. The software enables users to efficiently proofread and grammar check each line of the report, assignment, thesis. The software is a plug into Microsoft office products and requires an Internet connection.
It is also important to note that this is a software as a service product however, you may be able to use it to a certain amount per day free.
http://www.gingersoftware.com/