FOSS needs good documentation at this point more than anything else. There are dozens of superb FOSS applications out there which are almost unusable by all but experienced, technically knowledgeable users due to impenetrable and/or overly sparse documentation. New users, particularly new users migrating from Microsoft Windows, have neither the time nor motivation to learn the somewhat arcane terminology of man pages, nor to view one application's man page, then spend a day or so going through the same process in respect of another application that the first application's man page references (and so on, often ad infinitum).
Quality documentation written for non-technical users to be able to follow and understand is essential if FOSS is to make further inroads into the Microsoft installed base. If you have technical authors, or ordinary users who are keen on and understand FOSS and have above average documentation authorship skills and a few hours to spare, I am sure that many FOSS projects would be delighted to hear from you.