Hello. 
How have your previous JY experiences been?  I am quite nervous about meeting new people in such a short time, but looking around the boards, it seems most people are friendly and helpful. 
Do you have any must-sees/dos for the trip?  I love visiting galleries and museums so am thinking of visiting the Museuminsel or Kulturforum at some point, time-depending. 
There is at least one other person here who is going on the same trip - maggies...?  (I have posted on their thread re: Tube travelling times). 
Look forward to meeting you too.