It’s not easy to export all your data with Google Notebook’s option to export each notebook as HTML or Atom format. However a Greasemonkey script (requires Firefox Greasemonkey extension) comes to rescue and automates the tedious work by reformatting the mobile page and adding links to the HTML or Atom version of each notebook. The default format is Atom and you should use it if you want to edit the notebooks on your computer and then import the files to Google Notebook. It's a good idea to use the HTML format for archiving your notebooks.
Once installed, a link to “Export Notebooks” appears in the top right corner of the page. Now you can use a download manager like DownThemAll that saves all the files linked from a page or some of them to a choosen folder where to save the files, type nbid in the “Fast filtering” box and click on “Start”.
Peter Shafer wrote a similar script for exporting Google Docs documents.
Source:→ Google System