You (most likely haven’t) Heard of Geocaching…
I am not nerdy enough to do geocaching (read about it on geocaching.org… it’s basically a scavenger hunt using GPS), although I have thought about it. Upon reading xkcd (an online geek comic strip) one day, I saw a comic called geohashing. It was funny, although unless you are a geek, you propably won’t get it (as is the case with pretty much anything on xkcd). The algorithm calculates coordinates within ~100 miles of you based on the date and the dow jones average. The whole thing got seriously out of hand. I won’t go into it further, but you can see this link to understand the depth of ridiculousness. I wouldn’t recommend actually going geohashing, but I find it amusing that an entire online community is forming around it.