There's another celebrity investor on the block: actress-singer Selena Gomez.

The 19-year-old joins a handful of former MySpace executives, among others, in a $750,000 angel-investment round for Postcard on the Run. The Los Angeles-based start-up develops apps that let mobile users take pictures on their phones and turn them into actual ink-on-paper postcards at 99 cents a pop.

Gomez will also be a creative advisor to the company, which just launched the rather tween-and-teen friendly feature called "Smell Mail." The feature allows users to—wait for it—add a scratch-and-sniff sticker to their postcards for 50 cents. Available scent choices include pine, flowers, chocolate, bubble gum, suntan lotion, baby powder—as well as something called "teen spirit."

The company's founder is Josh Brooks, formerly of MySpace and He had in the past managed musicians such as Tori Amos and Queens of the Stone Age—perhaps the circles that led him to Gomez.

He started the company inspired by the 23,000 (yes, 23,000!) photos he had stored in his iPhone gallery.

He told in September: "I scratched my head, because in my alternate life, I'm so much better at printing and keeping up with photos I take. But, in real life, it just doesn't happen." He noted that nowadays people will leave home without their wallet and keys but won't go anywhere without their smartphone.

Other investors include former MySpace chief executive Mike Jones, former MySpace CEO Chris DeWolfe, former PriceGrabber CEO Kamran Pourzanjani, and Aber Whitcomb, MySpace's former chief CTO and co-founder.

The Gomez announcement might not have been a total surprise for the pop princess's 8.3 million Twitter followers. "Ummm im obsessed with the app Postcards on the Run!! I've been sending them like crazy lol," she tweeted a couple of weeks ago. (No word on whether her contract includes any tweets for the company from her boyfriend Justin Bieber, who has more than 14 million followers.)

"I've always loved the old-fashioned touch of sending real postcards, but I never have time anymore with my busy travel schedule. Now it's easy with Postcard on the Run," Gomez said in a statement. "The one thing that I always have with me is my smartphone. In just seconds, I can send personalized photo postcards to my family and friends right from my phone. It's a new way to stay in touch the old school way."

Other Postcard on the Run features include "signature," which users can do using their fingers as a pen, and GPS stamping, which will put a mini-map on the back of the card indicating where in the world the sender is.