Aside from satellite aberrations, and features on some fascinating places, prize for all round weirdness goes to the Flying Doughnut
(Google has improved the definition of images since this was posted, if anything it gets weirder close up).
Edit 2024: Google Sightseeing seems a bit broken, I hope it will be fixed. Here is a much clearer photo from Geograph of this little oddity.

Hi Tim,
Can you elaborate on your problems with Firefox? I use Firefox and Safari on mac and can see no problems with the site…
Cheers,
James
Hi James, I just took another look. I use the no script plug in, and I think this was partially blocking the map display page when I visited yesterday. When I permanently allowed script on the site it worked fine. So the problem was user error…. I have amended the post accordingly.