I'd give a quiz on the lecture material for today.

Or give the students who showed up extra credit.

You have a clear attendance policy, right? A contract at the begining of the semester saying what is expected of them?

It's college, not kidergarden. They don't want to show up, they can deal with the consequences of missing out. Getting pissed at them doesn't help and doesn't get them to not skip in the future. However, I've found that not caring what they do gets more people to show up. You don't get a bonus for passing them.