It's a good idea to have a card and be not shy in handing them out. I might have too many though.
There are many reasons to bring your business cards on a trip and hand them to everyone you meet.
Just make sure you hand the right card to the right people.
I carry three or four different kinds of business cards, plus my wife's cards, all waiting for the chance to be glad-handed off. I have my Microsoft card, my personal website card, my blog site card and the card I hand out for Suite. I also have cards for my photography. Then I carry my wife's cards for her Suite editing work, and the cards for her freelance work (here, she says, pass these out if anyone needs a writer).
It's a little shady-looking, shuffling amongst your cards to find the right one to pass to people. It's like, "Psst! Ya wanna buy a watch?" It's so much cleaner to smoothly pull a card from your pocket without a glance.
Best solution - have a nice little business card case and fill it with the card du jour. You have to guess ahead of time what card you will want for the occassion. Then you only have to play the shuffle if you guessed wrong...
