If only I had the time: WalletGlove
Wallets are annoying. They're easy to lose, hard to store (especially when it's too hot to wear a coat), and they're always in your other jacket. Not to mention that people try to steal them.
Wouldn't it be useful if you had a wallet you could never lose, was always where you needed it, and didn't get it in your way?
Introducing... the WalletGlove©!
The WalletGlove is simply a compartment stitched onto the back of a glove. The glove is fingerless so you can wear it in warm weather. No one will suspect that your money is there, and even if they did, it would be impossible to steal it without you noticing. You wear your WalletGlove on your 'other hand' (i.e. right hand if you're left-handed).
The only drawback I can imagine is that it won't hold much money (bills will have to be folded over twice, I imagine, unless you have giant's hands like me), and that it may bend, fold or mutilate your credit card (that could be fixed by reinforcing the pocket).
The actual manufacture, marketing and sale of this fine product is left as an exercise to the reader.