Though Google itself is not a very complicated one to remember it, but still there are many sub urls which need to be shortened to get them remembered. May be Google also aware of this as recently they have launched a Url Shortener only for Google Website with an extension as ‘g.co‘.
Here is what Google describe when you visit to G.co page:
You’ve arrived at this page because you typed or linked to “g.co”, Google’s official URL shortcut just for Google websites.
Whenever you see a short “g.co” link, you can trust that it will always take you to a Google product or service.
We also have a public URL shortener at goo.gl. You can use this to shorten up URLs across the web.
Though we already have a Google’s public URL shortener called goo.gl which anyone can use to transform any url in the world, but if a link have an g.oc in the ending, it will be a suerity that it will land to the one of the Google’s own page… a genuine page and is created by Google only.
While the goo.gl service is for the public to create and use the shortened urls, g.co is a service used by Google officials only.