One of my favourite little activities at big tourist attractions is photographing other people taking pictures of other people. It's a hilarious snapshot of human nature and our compulsion to document. The awkward smiles, the crazy poses, the smart phones held aloft above the heads of others: it's like photobombing reversed. (Although let's face it, photobombing in these situations is pretty fun too.)
When we were in New York, Chris spent a full twenty minutes photographing other tourists posing for photos in front of 30 Rock. It's an entertaining experience and the results are hilarious when you're weirdos like we are.