HappyPass, I asked myself (and others) the same question when I had been on the thread for a couple of months: how many aircraft types there is and are we running out of them.
There are some 24,000 aircraft listed in Wiki List of Aircraft (not all of them have a full article). We are now at 2,303 (status 1 April 2011) plus, so there is a lot of field to plough.