By popular request (thanks Phil Sutton!!) here's another 5 minute marketing idea for you.
I'm highly in favor of printing direct dial telephone numbers on business cards (especially if you have one of those icky automated attendants!). And some people elect to print their mobile and even home phone numbers on their business cards, as well.
I like to be accessible to my clients and prospects, too, so I can appreciate the gesture, but instead of pre-printing that info on your cards, try this alternate way of sharing that privileged information.
Add a few more seconds to your card exchange process by tell the kind person you are talking with (or mailing to) that they are especially welcome to call you at your personal number. Then write "Michelle's home 123-456-7890" right onto the card front or back.
This lets you use your business cards in a way that makes someone feel really special...like they are part of a small group of people who have that exclusive access to you.
Another little tidbit...I just got back from 10 days in Malaysia via Hong Kong and Tokyo (yes it was wonderful) and I'm again reminded of the gentle and honorable Asian custom of presenting and receiving business cards with two hands, followed by the careful study of the card you've just received (don't write on the other person's card or stuff it into your trouser pocket--these things dishonor the card which is considered an extension of the person, thus dishonors the person).
There is something really nice about this ceremonious way of acknowledging someone. In the US, or even in most of Europe, you certainly needn't bow or go to abnormal extremes, but try presenting and receiving cards with a little more panache to make the person you're exchanging them with feel a little extra important.