thanks for your reply

let's say I want to do the first you mention
(although I don't see any reason why I need to specify A,B and C websites and
not to apply this for all the webpages of all websites I visit)

how it can be done?
first, we need something that will "monitor" every webpage I visit, as I
browse the net 
this monitoring has to be very accurate ofcourse, which means it must not miss
any webpage even the webpages that are partially loaded etc

by "monitoring webpages" I mean to grab the text, links and files of every
webpage I visit
by "the text of the webpage", I mean the text that is highlighted/selected
when we click ctrl+A in a webpage (included any other "hidden" text, etc)
by "the links of the webpage", I mean the links that are grabbed when we hit
ctrl+alt+L in Opera or any other method that shows all the links of the
webpage (included any "hidden" links, javascript links, etc)
by "the files of the webpages", I mean the files that are included in the
folder that is created when we save a webpage which created an html file and a
folder (and any other hidden files, embedded files, etc)

as far as I know (and if you know something else, please inform me) the
available methods that can monitor web browser traffic are these:
javascript can monitor webpages as I browse the net (opera, for example, has
this javascript function:
document.addEventListener('DOMContentLoaded',function() { where it does things
when the webpages are loaded)
internet connection sniffer can monitor webpages as I browse the net, that can
sniff urls
web proxy can monitor webpages as I browse the net, as it works as a cache
proxy

then we need to apply filters to specify which of the text, links and files
are useful and then we need to save the filtered information

thanks