Psst! This is the next killer app for banking right here.

In January, customers of the $4.9 billion-asset First Financial Bank in Abilene, Texas, began paying bills by taking a picture of them with a smartphone or tablet. A few months later, U.S. Bank became the first big bank to roll out a photo bill pay service.

Some analysts see the start of something big—not merely one more thing people can do with a smartphone but a revolutionary change that could give mobile banking adoption its biggest accelerant yet.

The convenience of photo bill pay beats both paper checks and existing online bill-pay services, where the setup requires typing in a lot of information. "This is a way to take that pain out," says Mary Monahan of Javelin Strategy & Research. "You can take a picture and be done with it."

The Picture Pay service from First Financial comes from Allied Payment Network, which developed it with Malauzai Software and is bringing it to other community banks. It uses technology from Mitek Systems to read data from a bill and confirm the biller. U.S. Bank also worked with Mitek to offer its Mobile Photo Bill Pay service. If the concept catches on as expected, it could make even the increasingly popular remote deposit capture seem incremental.