uLouder - Modern Craigslist and Nextdoor for urban nomads
Grover - Rent electronics for a month & try it before you buy.
Explore nearby places for Airbnb - Discover must-see places when browsing Airbnb (Chrome ext)
Shelf Engine - Vendors get paid for only products they sell
Whereabouts - Write posts and chat (group or 1-on-1) with people nearby!
Origin Marketplace - Power hundreds of decentralized, peer-to-peer marketplaces