From Google Blog:
"Search is all about finding the answers you need. Unfortunately, some kinds of questions--like where you should stay and what you should do on your Hawaiian vacation, or what kind of digital camera you should buy, or what the latest treatments for arthritis are--can't always be answered in one sitting, or by visiting one site.
That's why we built Google Notebook--to give you an online "notebook" where you can organize all your research, add personal notes to it, and share it with others. Google Notebook surfs along quietly with you as you browse, letting you clip and annotate whatever text, images, and links that help answer your question, all without ever leaving the webpage you're on.
Also good for keeping track of your web research. Here is google notebook.
Ernster, the Virtual Library Cat