Mario's Top 3: 'Dick Tracy' watches, Snapchat and apps gone wild

TODAY's digital correspondent, Mario Armstrong, shares his "Top 3" gadgets and trends from the tech world for the week of March 3:

Martian smartwatch: This may look like a classic wristwatch, but the Martian Watch is equipped with a speaker and a Bluetooth link so that you can send commands and hold conversations via the watch and the smartphone in your pocket or purse. "Dick Tracy is finally here," Armstrong says. The Martian will make you feel as if you're really using the comic-strip character's two-way wrist radio. Find out more about the Martian and other smartwatches.

Snapchat's snap judgment: When you share a picture with a friend, the Snapchat mobile app lets you determine how long the recipient can look at the picture before it disappears, up to 10 seconds. This is meant to keep your friends from oversharing private or potentially embarrassing snapshots. There's a catch: The app can't prevent your so-called friends from making a quick screen grab and saving the image file. Nevertheless, "it gives you the illusion, and it can be fun from that perspective," Armstrong says. Find out more about self-destructing message apps.

Apps gone wild: One of the jaw-dropping tech stories of the week was the one about the 5-year-old boy who made $2,500 in iPad app purchases in just 15 minutes. Armstrong pointed out that the boy was able to rack up such a big bill in that short of a time because some apps can let you make add-on purchases without retyping the typically required password. To head off app-enabled shopping sprees on the iPad or iPhone, you can go into "Settings," then "General," then "Restrictions," and then turn off "In-App Purchases."