Unbreakable microwave safe plates?
One thing that hasn't been mentioned -- Corelle.

It's not completely unbreakable (and much like Pyrex, when it goes, it goes like what nico mentioned -- little tiny shards everywhere).

Supposedly, it loses its resilience to breaking over time, so newer plates are less likely to break when dropped as older ones, so this is one case where buying at a yard sale might not be best.  

I don't know how the durability compares to Pyrex plates, but it looks more 'dinnerware-like' to start.