Here is an interesting post on how to use business cards for notes on the road. It inspired me to order this from Amazon:
It's a "Blank Flash Card Dispenser Box Card Size 2'' x 3''" 1000 cards, and it will probably last me a life time. I like the small size, as two, three or five cards will easily fit in my wallet. (They are a bit smaller than credit cards.
You can never have too many ways of capturing notes.
1. The blog has other interesting ideas for "analog note-taking." I use both analog and electronic means, however.