>I understand NULLS have a special purpose... but I think I'm starting to abuse it. For example, if we have a text comments area that saves to a varchar field, would it be proper to use NULL if the user left the text area blank, or would it be proper to use a blank string?

I am not a big fan of nullable fields unless it is needed.
I prefer to store an empty string instead of a null.
Some people us nullable fields to indicate that the user did not supply information for that field (did not enter that textbox, if they entered the textbox but didn't type anything then an empty string is stored in the DB).
Just my $0.02. I don't think there is a proper way