I'm not much into social network gaming because I just can't find the time to keep up with them. But then along comes Gowalla, which is a location-based travel game. Now that's something I can get into! Basically, people use their GPS-enabled iPhone to create locations which other people can then "check-in" to and get a stamp on their virtual passport (apparently other mobile phones, like Droid, are in the pipeline soon). If that were the end of it, Gowalla wouldn't be much of a game. But there's more.
In addition to collecting passport stamps, you're also looking for achievement pins and collectible icons.
The pins are added automatically when you do things like complete a pre-existing trip... or check-in to a certain number of locations... or do some other task, like visiting 10 different coffee shops or something.
The icons are a little different. Some are permanently awarded for visiting specific places, like Powell's Books in Portland, The Space Needle in Seattle, or The White House in DC...
Others are found at random. You can drop these items somewhere so somebody else can trade their items with them... or you can put them in your Vault, where they will be stuck forever...
Unfortunately, once you drop an item somewhere, it's pretty much GONE until you find another one. It's not like the Pokemon Pokedex which keeps track of the items you've found. Sure you can put it in your Vault, but then you can't trade for other items. This seems to be a disappointing flaw, but I guess that's what makes some icons more rare than others.
Locations are created by Gowalla users. If you create a spot then drop an item there, you get credited as the spot's "founder." You can create all kinds of spots for all kinds of locations. As an example, here's a church, museum, and a grocery store...
It was fun wandering around town so I could create spots and drop items for fellow Gowalla users to collect and trade. Kind of like geocaching taken to the next level, I suppose. Though it's a quasi-virtual level which is still fun, but lacking the tactile thrill of uncovering a treasure.
In any event, if you have an iPhone and like to wander, it might be worth checking out...
NOTE: Gowalla abandoned its users (plus all the work we did) and closed up shop in 2011.