I am looking for a grammar-checking tool, i.e., something that checks for mistakes such as "two dog" or "a books". It has to work on Linux (Ubuntu). Also, since that I use macros to generate some of the prose, it has to somehow work with LaTeX. I don't believe that such checkers are LaTeX-aware, to it has to work with some compilation product of LaTeX: DVI or PDF.
If you suggest a grammar checker that checks plain text, please explain how to you extract the text. catdvi does a nice job, but it leaves some garbage, like page numbers.