Sorry, I seem to have been highjacking the thread to student-pseudos. Would it be inappropriate to amalgamate discussion? Drew Buddie seemed to be mentioning student anonymity, perhaps as well as teacher anonymity, and I joined after his post (I say, attempting to pass the buck?).
In language classes I emphasise that it is not important that one express ones *own* opinion and that students are free to draw upon personal experience, or enter into a fictious role when they are not happy expressing their own experience. Hence, language classes are not too much of a problem.
But when it comes to content classes, where there is, if not a right answer, a right direction or right style of answer, then it is not meaningful to allow students to drift off into fantasy.
I wrote a hack for 1.4.x moodle to make forums anonymous. Both students and teachers were free to give their name, or sign with a pseudonym. It seemed to work well, in that it was the only time in my recollection when students started to interact with each other in the forum, rather than merely with me (the anonymity/2ch effect)http://moodle.org/mod/forum/discuss.php?d=22530
Like you I wish to assess my students. The hack in question allowed me to grade the students on the forum, not knowing their real identity, but for these marks to show up in the gradebook against the students' real names. Of course, using such a device would allow me to give a student a unique mark and then check against the gradebook to see which student had been awarded that mark. And while aware of this fact (I told them that their grades would show up) the students seemed happy with that situation. I have not found time to re-hack 1.5.x alas. If someone does then it should be possible to allow both student and teacher anonymity.