When I was a kid, I was a Marvel comic book fanatic, but no superhero held my fascination like Spiderman. I horded Spidey issues. I drew pictures of him. My family has pictures of me posing as Spiderman as I pretended to walk on walls and swing from building to building.
30+ years later, my fantasy has become realized in Google Earth 4.3. Few have noticed this new feature yet, but you can swoop to the top or sides of 3D buildings, then jump from building to building ala my favorite superhero. To do this, right click (CTRL + click on the Mac) on the building and drag the mouse. You can swoop from building to building by doing the same. Learn more in the user guide.
You can also view a 3D building from different perspectives. To do this, click the middle mouse button (Shift + left mouse if your mouse does not have a middle button).