There was an episode of Monk a couple of years ago where the brilliant but obsessive-compulsive detective gets new business cards. When he discovers how much each card costs, he starts taking them back from people he doesn’t think really need to have them.
Many people adopt the opposite approach: they hand out their cards to everyone they meet, and take–and hoard–everyone else’s contact information. But all that gets you is a telephone book. When was the last time you went through your stack of cards and Outlook contacts? If you don’t recognize the name, can’t place a face, or know the person’s information is out of date, delete it. It’s not about having the biggest list. It’s about defining the value of each contact.