Nintendo knew what they were doing when it included the Street Pass feature in the new 3DS. What is Street Pass, you ask? Well, your 3DS comes with the ability to broadcast and receive Mii characters from other 3DS users as you pass each other on the street, in the grocery store, or in my case this weekend, at WonderCon, when communication is activated. Information shared includes your Mii's look, a custom message, and the last game you played on your 3DS. You're notified when you've collected a new character by the illuminated green light on the top of your console.
As you gather Miis, they gather in your Mii Plaza where you'll have the ability to play new RPG-style games with them and collect pieces to complete special puzzles. It's incredibly fun, and ensures that you'll want to take your 3DS with you wherever you go. I collected almost 50 Mii characters in the three days I attended WonderCon, and I'm kinda obsessed with getting more. Have you activated Street Pass on your 3DS yet?