Companies that have unused office space can sublet it to individuals or other small group swho need an office but can’t afford the full deal.
It’s great for independent contractors who want to have an office outside of their house.
http://openofficespace.com attempts to make these arrangements (and other more standard office space) easy to list/find. While it “kinda” worked for me, the implementation is really lacking. Lots of the results that came back were not in the specified area radius and some that WERE were not shown until I modified my location.
People listing $0/month is also quite useless for people who don’t want to have to call the agent to find out that actual asking price.
But still, probably a useful resource.