Having recently spent a few weeks in France, I noticed a practice that would solve this problem completely. It seems now to be the standard method of operation at all restaurants from the trendy "gastronomique" places (with prices astronomique) to the neighborhood "steak/frit" joints.
When paying with a credit card, the server brings a small wireless terminal directly to the table. It looks just like a compact adding machine, with a paper roll on the back, but with a card slot on the front, where you insert your card. If it's a debit card, you key your PIN on the keypad. The receipts are printed right from the same device, and the card never leaves your possession.
If devices like this were used in the states, you could presumably also use the keypad to add a tip amount to the check. (In France, where service is included, tips are a rarity, and when offered at all are invariably in cash.)