Monetizing under-utilized space?

[Jeff Rogers]

I enjoy finding creative ways to monetize normally overlooked spaces at my rental properties.  I've been successful at renting out detached garages on a few of my properties.  I'm soon closing on a multi-family property that has some extra space that's begging to find a better use.  Historically it was used as an office for the previous building owner.  First thoughts are finding a way for the tenants to use it for a fee, either rent the space monthly or create a space that can be rented on a per-use basis....or possibly rent to another non-tenant individual for office use of some kind.  Any creative ideas others have found successful?  I don't remember if there is a bathroom in the area or not, which of course is a downside.