Photosynth from Microsoft has been around for a while, but there has recently been a new beta release of photsynth 2 which you can find out mode about it here. It might not be the best software for creating 3D maps but its free and they are putting a whole lot of focus on making it super easy to use, just load the photos and your done. No need to georeferance things etc..
Have a look at this flyby of mount Everest
And I found another one taken from a multicopter of a country house in the UK which demonstrates how this can be useful for real estate fly arounds. Although this one is not all that great as images where not taken specifically for this task.