Here's something odd I noticed the other day... not as cool as the OP but kind of interesting...
http://maps.google.com.au/maps?q=-37...2,85.79,,0,6.2
Go one hop forward along Swan Street and suddenly you're underground in the Burnley Tunnel! Go one hop sideways along Wellington Street and you're moving sideways across the same tunnel... another hop and you're back out in daylight.
The strange thing is that the tunnel doesn't actually pass under that point. Maybe their GPS went haywire.