This DIY oil detector, essentially a modified metal detector, is the hottest new accessory for city-dwelling hipsters worldwide. Plus, it matches terrifically with a beard.
The metal detector is outfitted with a relatively inexpensive "combustible gas sensor" that can detect pockets of oil, and the creator notes that the entire mod can be completed for around $US100. This particular oil detector includes some green LEDs which we don't believe serve any other purpose than looking cool (as we deduced from the intro, "What good is your newly built metal detector without a little bling?").
Neighborhoods in which this mod is guaranteed to work include the Mission District in San Francisco, Wicker Park in Chicago, and any Brooklyn neighbourhood primarily inhabited by white people.
Disclosure: Your humble editor also has a beard. And square, plastic-rimmed glasses. This post is thus what is known as "ironic," which has little relation to the English term, "ironic." [Instructables]