Kitten War – cuteness overdose, and general time waster. The winningest and losingest pages are worth a look too.
Tangentially related: For a while at work if someone stepped away and forgot to lock their computer, people would mess with them so they’d remember to lock it (for security sake) next time they stepped away. (Yes, I’m aware how sad it is that this qualifies as humor/entertainment in the office. Worse yet, it is so common there is a term for the practice – goating) Some people would make it so your computer would reboot when you opened Internet Explorer, or make a fake pop up telling you that you had a virus, or other troublesome/distressing things like that. I would reset their home page to Kitten Wars. Luckily, goating is not practiced at my current project.
That’s right, kittens to goats and back to kittens in two paragraphs by way of computers in the middle.