If you receive a business card that has information of value to you, how long will you keep it, whether in your wallet, purse, desk, fridge, etc.?
Well, physically I keep the card for just a week. But the contents of which I write on my directory. You can never tell that you might be needing the services of the guy on the card later on. So, it would be wise to have it listed on your personal or business directory.
I have a portfolio made for business cards. I keep them in my wallet until I *feel* they're no use to me, then I put them there. Alphabetically. Yes, I'm weir
It depends if I m in constant contact with the person. Some people change their info fast or company they work for. So basicaly the best thing is to exchange contact in some social business networking website.