Leave it to technology to come up with a way to try to prevent us from spending too much (I wonder how much the technology cost, but that's a subject for another day).  Now, there are wallets that are designed to do just that!

"Managing your money will be a snap, thanks to new high-tech wallets that track your spending for you. Product designer John Kestner, of the Massachusetts Institute of Technology Media Lab, has devised a line of smart billfolds called the Proverbial Wallets. One of them, the Peacock, shrinks as your bank balance goes down and puffs up when your finances grow more flush. Another, the Bumblebee, vibrates every time you use it and the larger the transaction, the longer the buzz. A third, the Mother Bear, features a hinge that gets harder and harder to open as your bank balance shrinks." (Sun)