I want to write a Firefox add-on for advanced history tracking and bookmarking which will send URLs the browser meets during usage (and all the metadata available about the context) to a web service which will keep track of them storing in an SQL database for further access and analysis. I'd like to divide URLs tracked into 5 groups: those I explicitly click to bookmark, those I download by Firefox standard built-in download manager, all other URLs accessed, all URLs met on all viewed pages as hrefs, all other URLs mentioned in HTML sources of all viewed pages.
Any ideas of how to get those in an extension?