In a sign that we are living in a truly mobile world, mobile gift cards are taking off like crazy.

During the holidays, grocery store clerks cheered whenever Chris Sweis, the chief mobile officer at JunoWallet, showed up to buy gift cards. That was because he gave the stores some huge business, buying every single iTunes card on the racks in the store.

He took them back to the office so employees, like Abel Jimenez pictured right, could literally swim in a sea of gift cards. The team had to scratch off the gift cards, get the access codes, and put them into the company’s database so JunoWallet could give away an electronic version of the card.

Sweis’ company has turned plastic gift cards into electronic gift cards. Instead of storing them in your physical wallet, you can put them in a virtual one on your iPhone or Android device. JunoWallet created a popular mobile app that will let you store all your gift card information in one place and access it right when you need it. It’s like a mobile wallet that connects you with just about every merchant in the world.

For consumers, the JunoWallet is a simple iOS or Android app that can securely store the numbers and pins for existing gift cards from businesses such as Starbucks, Apple, or The Gap. You can redeem those gift cards directly from the device, which means you no longer have to carry a bunch of plastic in your wallet or purse. It also means you will have the gift card information when you need it, as it’s easy to forget gift cards at home.

I met Sweis on the plane coming home from the Consumer Electronics Show; he was happily exhausted from being so busy. He laughed about how he and his team had to work around the clock to keep up with demand, which started taking off around Dec. 17, just before the holidays. In the last 30 days, the JunoWallet app has had more than 220,000 installs.

Sweis had to charge the grocery store sales to his corporate debit card. Once, the first time he did this, he was only able to charge $800 worth at a time. And after a few times, the bank turned the spigot off. Sweis had to call and explain that his business was taking off like crazy. That was just a couple of months ago, but now the whole process has been made electronic, where the gift card makers can send codes over in digital form.

“We definitely are not going to the grocery store anymore,” Sweis said. “Those were exhausting days, when we were doing 14,000 cards a day back then. We are doing significantly more business now. If we had to go to the grocery store still, I’d probably go crazy.”

JunoWallet also lets you obtain promotional certificates that can be used for a variety of products and services. That means you can essentially get free money from JunoWallet through various promotions. Users have been able to convert check-ins, for instance, into points that can be redeemed for gift cards. You can buy gift cards directly from within the app, as well as give cards and certificates to friends. Or you can get bonus gift cards and discounts when you make gift card purchases.

The free app has taken off like crazy. JunoWallet is at No. 5 in the finance category in the App Store. The company has also just launched an Asian-friendly wallet, dubbed BambooWallet, which is at No. 21. The BambooWallet is a companion app to JunoWallet, where you can connect different accounts.

Along the way, JunoWallet has added some interesting innovations that keep the cycle of card giving going. Last year, the company set up JunoPoints, where users can get 20 JunoPoints every time they log into a location. One JunoPoint was worth a penny, and the threshold for redemption was 10,000 JunoPoints, or $100. The company set up a JunoPoints reward system with Foursquare for a limited time last year and will relaunch it across the board later. The experiment was positive but Sweis said the company pulled the JunoPoints system down for now.

Some places will give away bulk JunoCredits, or a virtual currency,  just to get people in the door. Users can trade around different points related to specific prizes (you may need four points to get a free product), so the JunoCredits are a kind of currency that encourages social interaction. The app has an “earn gifts” tab that lets you generate JunoCredits that you can then use to shop. Some companies can use the gift cards as promotions to drive new business into their doors. They can, for instance, get consumers to install apps through incentives such as issuing JunoCredits.

If someone installs an app or uses it a bunch of times, the consumer can be rewarded with gift cards sent straight to the mobile device. This cost-per-action model generates money for JunoWallet. The advertisers are happy because the user actions include things that help the brand, like getting on a company’s mailing list, becoming a fan on its Facebook page, taking a survey, calling a call center to hear a sales pitch, or an instant gathering of people communicating via text message. Sweis said there is a lot more opportunity to grow the business.

“We are incentivizing actions in what is called cost-per-action ad units,” Sweis said.

Sweis said his team plans to offer $10,000 in iTunes gift cards to be offered in return for certain mobile tasks to be done at the Macworld Expo next week in San Francisco.

Sweis, a self-described serial entrepreneur with failures under his belt, started the company in Chicago in 2009. He started with a vision and interviewed a bunch of programmers for the job. He was about to hire a team from India when he ran into Raghu Sastry (left), who became the company’s chief architect, who then introduced Sweis to his friend Jae Hoon Kim (right), who became chief applications officer. They started on Christmas Day. The company has relocated from Chicago to San Jose, Calif. Buddy Sastry helped create the security for the company.

“We all realized we had something amazing together,” Sweis said.

On Facebook, JunoWallet has more than 46,000 fans. It has 13,000 Twitter followers. Advertisers are knocking on the door to use the platform. Rivals include players such as Wrapp, Swagg and Blackhawk’s GoWallet. So far, JunoWallet has angel investors. But it may need to raise money if its business keeps growing like crazy.

“We’re working as hard as we can to keep up with the demand now,” Sweis said. “It is really testing us.”