ERD Designer

So what are you using for an Entity Relationship Diagran (ERD) tool? I'm teaching a class at the University of Washington and we're doing that part of the class now. I normally use Visio, but find it a little less than perfect for this. And some of the students can't afford to buy it, so I looked around for a free alternative. There's this one: http://ondras.zarovi.cz/sql/ which is OK but doesn't show the standard "crows feet" for cardinality. Of course, there are the industrial standard tools, but they cost a fortune.

What are you using?