Mapwing is a Web site that makes it easy to build, share, and explore virtual tours for free. With Mapwing you can: turn your digital photos into interactive virtual tours, share your virtual tours with friends, family, or the entire world, browse a gallery of virtual tours created by other people, connect with a growing network of Mapwing users.
I was sceptical, but have turned 180 degrees: very nice roundthrough. Free if you make a plan with max. 20 viewpoints, each viewpoint can have 4 pictures (around) and you can make hotspots in the pictures. All the pictures (hotspots also) can have comments and you can plan a route through the building.
It was very nice. Code to implement is given when finished. You can embed it in your website. Really very good.
The con is also a pro: you don't have the file itself, it is hosted with mapwing. Means less bandwidth, but also a dependency (what if they stop doing it?).