Viruses are duking it out. A new worm, Netsky.F contains in its code the text "Skynet AntiVirus - Bagle - you are a looser!!!!" (j00 r a l00s3r. 1 will pwn0r j00 - ::snicker snort:: I'm finding 1337speak terribly funny today). It then removes Bagle if its on your computer. Bagle.K, the other worm in this digital war has embedded in its code the text "Hey, NetSky, fuck off you bitch!"
My idea for recreational virus writing was a chain of virii that didn't do anything harmful- they just replicated and tried to kill other virii. There was eventually supposed to be a method of polling the virii and keeping score, though I never really got that far along.