Anyone knows a very precise GPS sensor?

I can understand what you're saying. I have not seen the same results with WAAS.

You're telling me an individual reading never goes past 10m from being correct. I've seen readings 20m off.

95% of the time within 1m? I will guess 50% of the time within 1m, which is not bad!

Where can we see the actual ratings for different GPS chip family/categories?

Here is our discussion about accuracy and precision, I would like to understand this, please help.
http://arduino.cc/forum/index.php/topic,118012.0.html