The other day I read a blog post from the 37signals blog, Signal vs. Noise, about apps they are using. One that really caught my fancy was Cardstar, hadn’t heard of it before and it really solves a consumer problem.Itt eliminates those cards you have on your key ring and in your wallet. Those small cards are a pain.

The app creates a digital replica of the barcode that is found on the card the store gave you. When you need the card to get a discount, you open the app and have it display the appropriate barcode. You get the discount and don’t need to hassle with the cards.

Let’s take this one step further. A barcode that is used for mobile payments. Could see PayPal creating this type of functionality. Lower fees for the retailer on transactions would be a big selling point on getting this implemented. Credit card firms may also do this to make payments faster and more secure.

Security might be handled by using two 4 digit PINs. One as a user ID and the other as a security feature. The user ID would allow for more that one person to use the linked credit card or payment system. Purchases could be tracked by user and made into charts and graphs weekly, monthly or yearly.

Could see a secondary user being a child in some situations. Their PIN would have spending limits and it would be easy for them to see their spending balance as well.

*This is just a rough idea that came to mind during or after reading the paper this morning.

*Many people have their mobile phone with them at all times.