Rachel and I have been chatting about trying to do a little geocaching instead of regular hiking. Today's XKCD comic presents an idea called geohashing. There is a formula to figure out a geohash location. The inputs to the formula are the date, that date's (or most recent) Dow opening, and the integer lat/lon of your current location. The formula includes an MD5 hash and is pictured below. There is an app already written to calculate each meeting spot and there is a wiki with more info.
I'm not going to bother to explain what all that means, but if you need more help, you can click on the links for extra learnin'.