Peeling off cash for a transaction can be sobering, an emotion that merchants loathe. They'd much prefer that you barely register that you've even made a purchase.

The new Starbucks Card Mobile App for the iPhone is a perfect example of a process that can suck money out of your wallet without making a ripple in your financial consciousness.

The app allows iPhone users to buy their morning caramel soy macchiato with the wave of their phone. A bar code will appear on the phone screen which can be scanned at the register. The purchase is taken off of their Starbucks card balance. (Need I point out that when you buy a Starbucks card, you're making an interest-free loan to the corporation?)

When the card runs low, money can transferred from a credit card wirelessly via the iPhone or iPod Touch. Users can also check their balance via the app.

The program hasn't yet been released into the wild. It's currently being tested in Seattle and and a couple of towns in California. Users get the same perks as Card Rewards customers; refills, free Wi-Fi and a tall drink with whole bean purchases.

If you make enough use of these perks, it could justify buying a card, I suppose. Me, I just seek out coffee houses that don't charge for Wi-Fi in the first place.

Is the mobile app convenient? Very. Ask yourself, however, how you'll keep track of those purchases.

The most important step in managing your finances, imho, is maintaining a constant awareness of how much you've spent, how much you can afford, AND how much you have left. Paying with cash out of you wallet may seem a bit inconvenient, but paying for merchandise with a wave of the phone can grease the skids that lead straight to the poorhouse.