I have used simple chat application (instant messaging environment) and found that it does help in improving writing skills. I have not published these results yet so can not give you any link.
Have a look at REF-N-WRITE scientific paper writing tool. This tool allows you to import text from previous papers relevant to the subject area in MS word. While you are writing your paper, you can just search for similar statements from other authors and inherit their vocabulary and language to improve your paper. It also comes with a library of academic phrases that you can readily use to polish your paper. Here is the link for the site.