Digit, the automated savings plan that socks away money for you based on your spending patterns and leftover income, is introducing cash rewards today for users who leave their money alone. If you don't touch the money you've saved in a Digit account for three months, the company will throw a few cents your way: 5 cents for every $100 you saved, founder Ethan Bloch says. Because Digit is not a bank, it cannot legally offer users interest; "rewards" are the next best thing. And with the average US savings account bearing an 0.17 percent interest rate, your Digit rewards account might outperform a traditional bank account.

If you haven't tried Digit yet, here's how it works. You sign up on the desktop web or on your phone and connect your current bank account. Digit creates a new savings account, backed by the FDIC, and manages it on your behalf. Every couple days, it will transfer a few dollars — $2 to $18 on average. When you need the money back, you send text messages to transfer it back into your checking account. (Aside from a rudimentary website, Digit is designed to be managed exclusively through texts.) And aside from the lack of traditional interest, Digit is free to use.

Digit won't say how many people are using it so far, but they have collectively saved $23 million — $1.3 million a week. On average, the service is designed to save about 5.5 percent of a person's salary. There have been some hiccups along the way — Chase Bank repeatedly disconnected its users' accounts from Digit — but for the most part I've found that Digit delivers what it promises. I've saved hundreds more dollars this year than I ever thought possible, and it's all been totally painless.

Digit users have collectively saved $23 million

In coming months, Digit will explore offering similarly automated services for other common financial challenges, including paying down debts and saving for retirement. And while Bloch wouldn't quite promise me that proper apps were on their way, he did tell me to stay tuned.

Of all the services I've written about so far this year, Digit may have gotten the biggest response — it was the rare service that my friends read about and then actually signed up for. If they complained about anything, it was that Digit accounts don't earn interest. With the introduction of rewards, they've got one less thing to complain about.