I put a GPS tracker on my boyfriend's mother's cat

Because it's neat to see how the cat moves about! Why is it a problem if it's "inexpensive" and "commercially available"?

If you write a blog post about that with more information and graphics, I'll upvote it too. This post has very little technical information. Some ideas:

* What device they are using? How they attached it to the cat? Photos of the cat :) ?! Battery use? Transmission range? Is it water resistant?

* Day vs night patterns? Weekend vs workday patterns? (The cat proabally doesn' care if it's the weekend, but thi changes a lot the patterns of the humans and that will probably affect the paterns of the cat.) One week patters superimposed with different colors? (Does the cat always go to the same places, or it changes the path?)