Since I don't have the scratch right now to go out and buy a GPS unit, I'm going to try another method of getting out and hiking around with a purpose: FidoCaching.
I haven't worked out all the details yet, but the idea is this: throw a dart into the Lost Pets section of the classifieds. Now, this
can't be truly random because some of the distraught owners have utterly neglected to provide enough information to know where to start ("Lost kitten, Manhattan?" Rotsa ruck.)
So find an ad with sufficient location information, drive out there and start beating the bushes! You're guaranteed to at least get a bit of a workout, and who knows - you might be able to return a lost and scared pet to his grateful owners, and earn enough reward money to buy a GPS unit!
Some ideas for implementation:
Carry a printout of the ad so that you can respond to challenges from the locals.
Carry the right equipment. Carry at least a leash and a collar if you're trying to find a dog. A cat gets heavy after carrying it around for awhile...take a cat carrier.
Carry treats and toys to tempt the animal to you.
Be sure to show the dog the leash before hooking him up to it. If he seems reluctant, make sure he's not going to bite.