I don't know if the title is intended to suggest it, but what I thought of when I read the name "Google Galaxy" was a virtual planetarium along the same lines of Google Earth. Think about it. You can click and drag to look around the night sky, and when you zoom in, the all-sky image is replaced with high resolution images of star clusters, nebulae, galaxies and more. You could have different overlays for different frequency observations (radio, IR, microwave etc).
You could have tags on objects which you could click on to read more about the object, and link to research papers on the topic etc. You could also have an overlay which you could program to represent the horizon from any location on earth at any time of the day.
This would be such an AWESOME astronomy tool, and great fun to play with! I'd love to see such a thing become reality