My first thought after seeing GiftRocket: could I give someone a gift certificate for some random place, like the top of a mountain, so they have to climb the mountain to redeem it?
Edit: Here's another one. My brother, who lives a couple hours away, rarely visits. Can I give him a gift certificate to my house?
You can buy your brother a GiftRocket to a place right next to where you live, like a coffeeshop down the street. Yelp also has a lot non-businesses. For example, here's one in the middle of the Presidio in SF:
Edit: Here's another one. My brother, who lives a couple hours away, rarely visits. Can I give him a gift certificate to my house?