Perhaps in addition to doing surveys, if you want user feedback anytime, you may want to include some sort of submission form akin to the one asking for questions for comments/suggestions.
@Ceiling Cow That's a good point. Can you recommend any services that would let me just drop something like that in? I have a formspring box, but nobody seems to take advantage of it.
I wish I COULD suggest a better service. (All the methods I'd know of doing it are, surprise, for forums.) Perhaps just edit the text for the Formspring box to include comments, and in future layout renditions make sure the Formspring box is more apparent.