Everyone amasses business cards. We're afraid to throw them out. But there's little benefit in saving them in a jumble in your drawer. Before you think about "What's the best place to put them?" ask "Would I really need this again, and if so, why—and when?" Be firm; get rid of cards from people you are not likely to contact in the future. If you have a great many business cards, it can actually backfire—the more cards you have, the harder it is to find a specific one when you need it.
Once you've decided which cards are keepers, jot a note on back of each card stating where you met the person and what you might contact them about. This should be done as soon as possible, especially if you return from a networking event with a pocketful of cards; otherwise when you come across the cards later, you'll have no clue who these people are. Don't use plastic business card books with a dozen or so slots per page—it's impossible to keep cards alphabetized.
If you want to stay low–tech, use a Rolodex with alphabetical tab dividers. Alphabetical order is easy for people whose names you'll recall later, but what about service providers who are recommended to you that you're merely keeping in case you need them later on? Let's say your friend recommends a great cyberlaw attorney named Joe Moon. If you file the card under Moon you won't remember the name. File the card instead by category—under L for lawyer in your Rolodex. Do the same for plumbers and accountants and anyone else you might do business with.
It's much more effective if you're ready to update your organization efforts to use contact–management software (Outlook, Act, Goldmine, Maximizer are some popular brands). This gives you the best of both worlds—if you tag Joe Moon's record with the word "lawyer," you can locate him by looking up "Moon" or "lawyer" and find him either way.
Contact–management software provides almost unlimited room to type notes on each contact. Used fully, contact–management software keeps a record of all your dealings with each person, capturing phone conversations and email exchanges. It permits you to slice and dice your data in a variety of ways. You can also search for all referrals sent by a certain person, all the prospects who phoned you in July, all clients in a certain zip code, all clients who spent over a certain dollar amount, etc.
If you have a great many cards, you may not want to type them all into your software. There are small, inexpensive scanners made specifically for business cards that capture all the text information on the business card (name, company name address, phone, fax, and email address) and feed it directly into your contact management program. Monitor the accuracy of the card scanners: they are often thrown off by graphics, unusual fonts, speckled paper, etc., so it can take time to get the hang of scanning cards accurately. Card scanners probably aren't worth the bother if you have only a small number of business cards.