One of the most entertaining sites on the internet has to be eBaum's World. You can seriously waste hours watching funny videos, amazing videos, playing games, magic tricks, they have everything that you could possibly want to waste your time doing. You should definitely check it out. Here are a few of my favorites from the site:
Sand Sicaf--This video is an amazing piece of art. It's like 8 minutes long, but worth every minute. Play it with sound too. This is probably my favorite overall.
Cup Girl--If you've never seen people that can stack cups, check this out. It really is amazing.
Aicha--This one's a favorite for me and the fellas. This guy makes a complete tool of himself singing about a girl. Unreal.
Hand Sex--This one is just wrong, but it's very impressive. Someone is extremely talented, and must have been extremely bored.
Super Mario 3--A must see for old Mario fans. This guy beats Mario 3 in 11 minutes.
Robot Dance--This guy does an incredible robot. It's sweet, check it out.
Mario Piano--More for Mario fans, and music lovers. This guy is amazing on the piano. And yes, that is a blindfold.
Games--Big waste of time here.
Trippy and Scary--Don't play with this one if you use drugs. A crazy illusion.
Okay, so I've gone nuts with the links, but there really is a lot of neat stuff on this site. So don't forget to check out Ebaum's World.