My Favorite Internet Week 2
This website has you search for an invisible animal using sound. The sounds get faster and louder when you're near, and clicking on it awards you a point, and more points awards with new animals to look for. I don't know what's beyond the goat because my ears can't handle much more and I'm not gonna make it to 50 points.
This website allows visitors to create their own Pac-Mazes, that join other mazes on a giant map where you play Pac-Man on. With all the people who submit maps, it could be seemingly endless.