I personally have revised and edited a handful, but it has been a while. They were all interesting and worthwhile projects, though - stuff I hope got patented or comes on the market.

We'll write almost anything - the way our site works is, users post a project and then the writers bid. So if any of our writers has the time & qualifications to do it and the client likes the price, then we'll take it on. I've personally worked on letters about traffic tickets, written copy for online stores, B-plans (business and birth), content for MOOCs, recommendation letters, and once, a sex diary.