I am not an extreme couponer but I know a lot of you are.  I found this app that is available for free on the iPhone and Android phones.

If you never remember to bring the coupons when you go shopping, SnipSnap is an app that digitizes and organizes them on your smartphone. With SnipSnap, you just open the app and use your camera to scan the coupon. SnipSnap will convert the barcode on the coupon photo into a digital barcode that you can scan at the register. The app also collects and organizes all of the coupons that every other SnipSnap user has added, and lets you download them to your phone. In the settings screen, you can even enable background location awareness so the app can remind you when you're near a store you have coupons for, or you can just choose to be notified when one is about to expire.

SnipSnap is free for the iPhone and Android phones.