Youtube.com and meatcafe.com - vblog webites. post your videos and watch other people's videos. Anything from music videos to home jokes. Have fun. Really good!
Watch my VIDEO

panoramio.com - upload pictures of places which then can go on Google Earth. Really funny.
couchsurfing.com - Find other people from around the world. It a worldwide network for making connections between travelers and the local communities they visit.

whoopy.com - Similar to panoramio, but instead the pictures go on the website's map. Take pictures of places and the upload them to place you took the picture.

digg.com - rate anything which people post. It's mainly about cool news and websites and movies, books and music. Quite cool!