Recently I added a second computer to my Dropbox account. Doing so I made the following screenshot, which I have to share:
Students and employees from educational institutions get double free space bonus for refferals, by the way. To register for this programme is possible here. You do not necessarily need a .edu mail-adress, as pointed out. I registered with my @mytum.de mail-adress from the TU-München and it worked without any problems.