Like announced earlier on the serendipity blog, fellow usability expert Joachim Harloff is currently trying to improve the listing of Serendipity Plugins so that they are more accessible to users.
He needs your help to fulfill them. Initially he planned to personally meet with serendipity users, but this proved more complex than initially hoped. Thus he has created a smaller, text-based version of it.
You can download the file at http://www.softuse.com/serendipity_sorting.zip. It contains detailed instructions. You can also feel free to personally contact Joachim about any questions you have.
Joachim estimates this questionnaire to take you about 1,5 hours of your time. You could greatly help to improve the serendipity usability, so please participate! Joachim wants to evaluate your responses starting on September the 8th.