Besides Google Search, Google has numerous other online services. You can access and use all services using login details of a single Google account. Google has made things easy trying to view the status of all Google services your are using with your Google account through Google Dashboard.
It shows list of different Google services and associated details. This include: Account details, Alerts, Calendar, Contacts, Custom Search, Docs, Gmail, iGoogle, Orkut, Picasa Web, Google Reader, Google Talk, Web History and much more. Access Google Dashboard at google.com/dashboard and login using Google account. Here is video explaining it all: