>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?

Someone said that "nulls are evil" which I do agree. IMHO do not use a NULL for such a case and reserve to places where it does have meaning (do you really care difference between a comment that is null or blank - what would be an entered and blank comment? a space? Ugly ugly ugly).
Cetin