Mari, how good are you about keeping your wallet where it belongs? Maybe not the stuff inside, but the wallet itself? I propose a wallet with a chain.
I have a wallet chain so my keys and wallet are all in one unit. I also keep a bunch of extra keys that don't go to anything on the chain (including a fire extinguisher key!) If I drop it, it makes all kinds of noise so there's no way I can miss it. I've gotten to the point where I know something's not right if I'm not carrying that 3 pounds of wallet and metal, so I never wander without realizing I don't have my wallet and keys. It also makes a pretty decent weapon. It's like having your own personal spiky ball on a chain that no cop will question you about having in public or using in your defense. Tried and true!
