If you recall services like Couchswap, then you'll appreciate a new, similar service called Better Than the Van. It's a niche "couch swap" search engine that's designed for band members on tour. At Better Than the Van, you can search for kind souls willing to give up their spare bedroom/sofa/floor space for roaming musicians. There are a good number of parameters you can set for searching or listing your place, such as age range, days of the week, and photo only filters, reminiscent of the type of search options you'll find on Roommates.com.
Given the nature of touring musicians, this particular niche is quite useful and makes sense as a service. The other practical niche for such a classifieds search tool is for travelers, but I've found in my limited experience that the artist community may be more readily adept for such a service.