At times of uncertainty and displacement, self-storage becomes a hotter commercial real estate sector. Even as the pressures from the recession have begun to wane and demand has stabilized, the sector still has plenty of run room. Look at World Class Holdings' sale of a 64-property self-storage portfolio to CBRE and facility operator William Warren Group/StorQuest for $588 million. That's a lot of spare mattresses, old bicycles, and boxes of books that are waiting for transport to a new location.

There are clearly areas where self-storage is overbuilt. But many more where more could be used, or older systems upgraded. For landlords, there is an option that seems like a building owner's equivalent of a rideshare transportation service—leverage an existing physical asset to make money you might not have otherwise.

A company called Stuf works in a handful of cities and partners with landlords who have some extra room. The company turns the space into self-storage units. They cover setup costs, recouping the investment inside of eight months. After that, Stuf pays the landlord a percentage of revenue.