Ideas needed for back of business card

I am in need of ideas.

Soon I will be making some business cards to use when I network with O&G Brokers. I have a graphic artist for the logo, but I always thought a clever thing to get people to keep cards, at least a little longer, was to put something useful on the back. For example, I told one of my dealing companies to put the basic strategy for BJ on the back of the card. Doubt they did it because of me, but they later did it.

Anyways, I need some ideas. I would like to put an "inverse table" for deed calls but so far no math wiz has been able to crack the simple code for that one. It needs to be words only as I feel a graphic on both sides would be like a coin with two head sides, you just don't do it. I could do measurements of acres per section and covert old to new measures of perches to feet. But any other ideas?

Remember, this is the back of a business card, needs to be useful but small.

Phone numbers to all the local government offices, concerning land stuff/ titles whatever? Or something like that?

Quote: rxwine

Phone numbers to all the local government offices, concerning land stuff/ titles whatever? Or something like that?

Was thinking of that, might be too many to list. But glad to hear a second.

And thence to the point of origin.