The standard size of favicon is 16 x 16. To display a favicon you need to add a rel attribute in the head section of website and it usually place in the root directory. In Internet Explorer 7+, Mozilla Firefox, Opera and Safari favicons are displayed in all available tabs
Ok Enough.
Its not long ago that Google change its main Favicon. The old Favicon is a Capital G in a box, but the new one is small purple g.
So I decide to collect all the FAVICONS of the services or websites that are owned by Google. I am not sure that I got all of them but these are the maximum I can find. And Yup I do found some interesting stuff too. :)
GOOGLE CURRENT FAVICON
GOOGLE OLD FAVICON
These Pages are still showing the Old Google FAVICON.
https://adwords.google.com/support/
http://checkout.google.com/support/
The internal Pages from these pages also shows the same old Google Favicon.
NO FAVICON:
Yes these are the pages which don't have any Favicon.
http://picasa.google.com/support/?hl=en
http://sketchup.google.com/support/?hl=en
http://earth.google.com/support/?hl=en
PRODUCT BASED FAVICON:
Google Docs
Google Pages
Youtube
Blogger
Google Desktop
Orkut
Gmail
Here is the Google Help Center Page from where you can see the Products Google Offers. LINK