I actively encourage my employees to stay home when they're sick. I realize we all can't work in these strange utopias of logic, but losing one guy for a week is much better than him coming in and getting 3 other people sick for a week. From a pure numbers standpoint, I don't get how people don't see how it's a GOOD thing to tell people to take care of themselves.
One of my only office pet-peeves is when someone shows up to work next to me with an obvious illness. Then I get sick. Arrrrrrgh.