Speed Runs are a form of art. It's something anyone can do but only few can master. It's something that is often better to watch than a movie and something that will make you fall out of your chair right after seeing how a game that you've completed a thousand times gets destroyed in few minutes.
If you're interested in checking out some incredible performances, check Speed Demos Archives (the day I have found it was one of the most beautiful). Fallout completed in 9 minutes? Quake in 13 on the highest difficulty level? Diablo in 6? Nothing is impossible.
There are some amazing runs out there and I just thought it'd be good to mention them for those who never had opportunity to watch them. However I'd like to ask not to come here and criticize the idea of Speed Running. Some people just tend to say things like: "there's no fun in running through game". Well, I assure you that guys who do it have fun with a game first, now they are just trying to have fun with it in a different way.