Creativity at the expense of functionality

I have an exhibition next month for which I need to produce some business cards. So for inspiration I have done a bit of surfing, and courtesy of Eyes on Creativity I stumbled across the business cards photo-set on flickr.

The set includes over 480 photos of some of the most truly imaginative business cards. All of them are utterly creative, but some of them cross that line where creativity comes at the expense of functionality. Here are a few examples:

Clothes peg business card
Scrap of cardboard business card
Chewing gum wrapper business card
Scratch and see business card
Embossed scrap business card

Personally I give all of these maximum points for originality, but if the objective is get your name remembered I’m not convinced these will have the lasting effect of a more conventional business card.

How creative should a creative professional be?

Are any of the above business cards good or bad designs? How important is originality to a creative professional’s card? Is there a danger of being overly unorthodox?