Do you stay friends with your ex after you break up with them?

When I dumped someone (or got dumped) I immediately wanted to just go on a vacation somewhere so I wouldn't have to see the person! To me, when a relationship was over, I really wanted to move on it to the point where I didn't even want to see the person out somewhere.

That's not completely realistic, obviously. If you live in the same city you are bound to run into someone you went out with eventually. But when you do, how do you handle it?

There's a great article I caught recently that describes how to handle bumping into an ex. It gives advice on what to do if you're the dumper or dumpee.

Now that I'm in a happy relationship, it doesn't bother me to bump into people I used to know. I may stop and say hello, or just nod at them from across a room. Most of the time, however, I just silently acknowledge them and hope they are as happy as I am.

How do you handle it when you bump into an ex?