What Can You Do With a Mac Virus?

I was reading slashdot when I came across this laugh out loud comment on apples new "Macs are so much sweeter than PCs" ads. They talked about viruses briefly and someone commented that there had been a few mac viruses in the past five years, but the problem is as soon as it gets to a PC it stops so there's no real userbase for it. However, (the funny part) you could probably take out a small art school or advertising agency.

Oh gosh I'm so cool.