I'd love a "where did I get this tab?" function that would save the full context of where you opened each tab. So if you're scrolling in facebook and twitter and email and you open 10 tabs from links in various messages, then later when you look at one tab and wonder where you found it, I'd love a browser function that saved a block of text or maybe a screenshot (so it would still work even after you closed the tab the link came from) including both before and after where the link was (at least a sentence either way, maybe up to a whole "message" including the user who sent it, if it's from a site like facebook/twitter/gmail).
So then you could ask "where did this tab come from?" and (unless you had originally entered the URL manually) it would show you the message from your friend on facebook/twitter/email with the paragraph or even the whole message that included the link from which you opened the tab, with the link highlighted. That would be so useful!
I haven't been able to find a browser extension to do that (though the Tab Origin extension does a very minimal version: it will show you which other tab you opened a tab from--but only if the original tab itself is still open). Maybe it would involve saving too much data for an extension but could be implemented by the browser itself?