List of all Google Services

Google Search History
In Google search history we can browse and search over our past searches, including the web pages, images, news headlines, and Froogle results we've clicked on. We can also remove items from our Search History at any time by using Google Personalized Search.

• Why Google Search History is Awesome:
• There is some form of search query clustering.
• Google Search History - In Results
• You only have to log into one Google service for the search history to be activated - and this is good, otherwise I'd always forget.

http://www.google.com/searchhistory

Google Sets
Google Sets is a Google service that takes related things entered by the user and tries to find other things that will fall into the same category. Google sets are a way to browse the web's implicit ontology. What you do is simple: you enter some terms which you already think of as instances of some class. Google then returns you what it thinks are the other instances of that class.
http://labs.google.com/sets

Google Site-Flavored Search
If you have a web site that deals with a specific subject, says Medicine, your visitors would naturally welcome any additional service for providing them further information on the subject. For example, a search service that produces a customized search output with a focus on the site's content will certainly benefit the visitors. Google's "Site-flavored search that uses a Google search box to deliver custom web search results'' has been developed for this purpose. To integrate this service on to your site, access the link at: http://www.google.com/services/siteflavored.html, select the relevant category/sub-category fields applicable to your site and click on the `Generate HTML' button. Now, you will get a few lines of HTML code that can be pasted on to your web page for installing a `site flavored' Google search box. If you search through this box, the initial set of results will be the ones related to the content of your site and to display these results distinctly they are preceded with small colored balls.
http://www.google.com/services/siteflavored.html