Names on Cards

What do people do when suddenly there is no power in the office?... I decided to sort out business cards I've collected in the course of last couple of months. And in the good spirit of responsible consumption, I decided to re-use the card holfer by talking out cards he must have collected and sorted quite some time ago. I can see many of them are quite dated judging by the telephone codes which changed years and years back. The card holder is now stacked with cards I collected but what do I do with the old cards? Shred them?... Bin them?.. Shove them to the far end of the desk drawer?... wouldn't that be nice to send them back to their owners, to the people whose names are printed on them with a short note - Surprise! please have your card back, sorry, I don't think I'd need it, you can give it to somebody else instead?...