TerraCycle

Not only can one man's trash be another man's treasure, it also can be another man's $1.2 million. At TerraCycle, a company originally created by two Princeton University students for a business plan competition in 2001, that's exactly the case: Other companies pay them to take their non-recyclable waste and turn it into treasures—often practical items like tote bags, umbrellas, and notebooks—for resale to the public.