Deepleap is a browser-based web surfing companion application. Among other functions, it allows the display of useful "Metainfo" for the site you are currently surfing.
This "Metainfo" tab in Deepleap allows quick access to the site's home page, search function, site map and "What's new" page. A site communicates this information to Deepleap via a deepleap.xml file.
The DeepleapMetainfo Zope product provides a handy way to create, maintain and register your deepleap.xml file with deepleap.com.
Read the full documentation
If you want to find out a bit more about Deepleap, you could start with this article I wrote on my O'Reilly Network weblog giving my first impressions on Deepleap, and linking to various explanatory messages from their employees.