My college roommate and I embarked on a social network(elephantunderground) to change the way people collaborate/share/media online. This was before RoR and much of the web advances. It was more ambitious than we were able to handle honestly. Then we created yourbarguide. A bar scene type yelp social network competing with Yelp but we could not monetize. He went on to create an online store called Revzilla and is CRUSHING IT. Selling Motorsport gear. Found a nitch(there were no real competitors), had the knowhow, and is growing like a weed. Sell something, drop ship, and grow!