I used to not call in sick but I got over it after seeing other coworkers with that same work ethic, working while disgustingly sick and spreading germs everywhere. Also I hate driving in traffic while sick.
After the swine flu scare, we were pretty much told not to come in if we're sick. But we're also expected to go to the doctor, and that is just a waste of time and $15. My dr will ask me what's wrong, tell me it's probably some kind of cold and to come back if I'm still sick in 3 weeks.
I usually email everyone when I'm sick. It's usually before office hours since I'm deciding about 2 hours before I start whether it's worth getting up and driving in. Then I usually spend a few hours on email anyway, so they get some value out of my paid sick day.