At each stop on our recent Colorado/Wherigo tour, I've played equal parts Santa and Grinch. I was welcomed with open arms when I was explaining the Colorado 400t and its preloaded topo maps, paperless geocaching and wireless data transfer. I really became the star of the show when I was announcing the winning raffle numbers and handing over a limited-edition Colorado/Wherigo geocoin. But then I was the bad guy when I explained a few ground rules. 1) You can't get these geocoins by trading with me. 2) One person, one coin. 3) When my pockets are empty, the raffle is over.

But now I'm loosening the pursestrings. We're going to give away a coin a week to the weekly winner of our Wherigo Builder contest. The rules are easy. Build a Wherigo cartridge at Wherigo.com and send an e-mail to garminblogs@garmin.com with a brief description to let us know it's there. (Click here for detailed rules.) I'll team up with Brad the Engineer (the brains of our dynamic duo) and pick a winner each week until further notice. And that's just the beginning.

The best part about this promotion is that it's a gift that keeps on giving. Not only do you have a chance at a coin, but once we all start building Wherigo cartridges - they can be location-specific or "play anywhere" activities - each of us will have a better chance to try out other people's cartridges. The most important thing to remember is to be creative when you're creating a cartridge (that's what we call Wherigo activities, though it's a downloadable file - not a physical cartridge).

Invent your own role-playing adventure. Script a storyline to be enjoyed anywhere. Break out the history books and create a local tour. Stop and smell the flowers - and then guide someone around the botanical gardens. The only boundaries are your imagination.

So go to Wherigo.com and learn about the Wherigo Builder program. Build a cartridge and upload it to Wherigo.com. Send an e-mail with a brief description to garminblogs@garmin.com to make your entry official. We'll announce the winner each week, and a geocoin will be on its way to your house. And regardless of whether you win, we'll post the description from your e-mail so that more people can try your cartridge. And for those avid geocachers interested in trying out Wherigo, you'll be thrilled to know that there's even a Wherigo cache type! Check out Wherigo.com for details and start building!!

Click here for the complete set of rules.