Tony Ruscoe found some new Google services while trying to log in to sandbox.google.com. It seems that Sandbox accounts are another kind of Google Accounts, used by those who test new Google services. Tony explains how to create a Sandbox account, although you can't actually test the products.
Here are the not-yet-released services :
Google Events - http://www.google.com/events
Examples of events already hosted are: Doodle 4 Google, ACM World Finals.
Google Guess - this might be a new kind of search more AI-based
Google Online Assessment - http://www.google.com/goaexam - an online skill assessment tool?
Google Real Estate Search - homes for sale, mortgage calculators (extension of Google Base?)
Google RS2 - this might be related to the new version of Google Translate
Mobile Marketplace
An interesting article that explains the term gives some hints: "For example, consumers can design their own clothes and accessories (including jewelry) online. Soon, they'll be able to virtually try on clothes or rings and e-mail the images to family, friends, and strangers for feedback before deciding whether to buy."
Google Workplace - this may be the name for Google Office
You can create a Sandbox account at: https://sandbox.google.com/accounts/NewAccount.
To see the names of the services and add them to your account, you can go to these links: ev, guess, goa, re, rs2, mmp, wf that follow this pattern: https://sandbox.google.com/accounts/Login?service=[code] and click "Continue" for each one. Then if you go to My Account, you'll see a list similar to the one in the screenshot. You can use this new Google Account only if you log in at sandbox.google.com.
Of course you can't log in to the services you've just added. Only Google testers can do that. But it's interesting to see what the future may bring.
Update: Google fixed this, so you can't perform the actions described in this post anymore.
Related:
Other secret products
Evidence of Google Office for Businesses
Old Google homepage still live