The New Scientist has an article in their blog about an artist who is mapping people's emotions. Basically, he's got people hooked up to simple arousal sensors on their skin and has those sensors plugged into GPS units. From there, he aggregates stress levels across a number of people. Perhaps even cooler, he's allowed the people with the sensors to tag what they were doing or how they felt at certain points. Check it all out at the project's site to download and view the data via Google Earth.