I wouldn't go way out of my way to find one if I were you, downloading other people's maps is cool for ten minutes before you realize they all suck. If you are halfway decent with the park editor you'll be able to spend 20 minutes making a couple features and end up with something you can probably play for more than an hour. I find most of the parks online are way over the top and don't flow very well. Just put all the time you would spend trying to get an activation code into making a sick park to mess around in.