Who hasn't played this game? "If I give up x, I can justify buying y." At our house, after two decades the game is mostly now limited to big-ticket items. For example, "If we don't replace our 11-year old Toyota, we can take a summer trip to the U.S. Open."

The basic premise is that the extra three grand you DON'T spend on the new car essentially pays for the vacation, making it seemingly "free" and more guilt-free. It's a common and powerful principal of consumer behavior.     

Piggymojo's just-launched service taps into this psychology and gives it a mobile twist. The startup uses text/Tweet-based data input so it's easy to track all the expenses you've avoided during the day. And because it takes just a few seconds to tap out a message, the principal can be used to track even trivial daily savings that can add up over time.

For example, if you decide to start brown bagging lunch instead of hitting your normal lunch spots, you can track the savings by Tweeting/texting to your Piggy Mojo account:

Packed own lunch, saved $5 (or on Twitter, "d piggymojo 5 lunch not out")

Drank free office coffee, saved $2.75

Read office newspaper, saved $1

The service collects all these messages and tracks the total amount "saved." The totals can be applied to various savings goals to measure progress. The site uses a unique photo mosaic to visually represent goal progress. You can choose from dozens of exisiting photos or upload your own. As you build your savings, the photo gradually fills in until it's complete (see screenshot below).

You can add your spouse/partner to the account so both of you can contribute towards the savings. There's also a way to set up "recurring savings" so you don't have to constantly text repetitive items. For example, if you cancelled your cable TV, you can input the amount saved once at the Piggymojo site and it will automatically credit your account each month (see second screenshot).

There's also a social piece, allowing you to bring friends and family into the fold. Piggy Mojo will automatically send them a weekly progress report on your goal, providing that all-important peer pressure to your spending discipline.

Relevance for netbankers
Currently, the site is not hooked to an actual bank/CU savings account. The user is responsible for actually moving these fictitious savings amounts to a real savings account for later use. But this concept would be much more powerful if every time you texted "saved $6 at lunch" that six bucks were actually transferred from checking to savings.

Piggy mojo goal-tracking via completing picture of your goal (1 June 2010)
Note: The arrows point to the color sections that have been completed, visually demonstrating that I'm about 7% of the way to the goal

Recurring savings input form

Notes:
1. HT: Credit Karma blog
2. For more info, see our Online Banking Report, where we wrote about various ways to leverage your online/mobile channel to boost deposits in late 2008 (here).