I print business cards on the computer as well. On the back, I print the name of the kit, type wood (along with a little detail on the wood), and type refill. I do that on all the ones I sell or give away because I use woods that most people have never heard of.
Since the cards come in pages of 10 and won't go back through the printer cleanly with 1-2 of them gone, I try to wait until I have several that need printing before I print. Any cards that don't have info on the back go into the card case I carry with me to hand out.