NASA has used Microsoft's Photosynth technology to create interactive "3D" image collections that allow you to explore the ISS (inside and out) and JPL's new MSL (Mars Science Laboratory) rover. This technique essentially maps a large set of photos from multiple views onto a sort of 3D "frame" and provides you with a graphical browser that allows you easily and (fairly) smoothly transition between the different views.
While it's somewhat like walking or flying around the object, and it preserves the full resolution of the original photos, it really doesn't give me a good 3D impression. Photosynth may be more flexible (you can use collections of photos that were not intended to be joined in this way, even taken by different people at different times), but it doesn't seem very smooth and natural to me. I've seen some QuicktimeVR "virtual tours" that I like a lot better, like this space shuttle interior.