I've written before about how I use my browsing history to keep track of what I've read , although that only partly works in this era of websites making visited links look the same as unvisited ones. However, there is a little problem with using the 'visited' status to keep track of what I've read, and that is that visiting a web page doesn't necessarily correspond with actually reading it. Specifically, sometimes I run across a potentially interesting link but I'm not sure I have the time to read it right now (or if it's actually going to be interesting). If I follow the link to check it out, it's now a visited link that's saved in my browser history, and if I close the window I've lost track of the fact that I haven't actually read the page.
For years I used various hacky workarounds to take quick peeks at pages to see if I wanted to actually read them. Recently it occurred to me that I could use Firefox's Private Browsing mode to conveniently deal with this issue. If I'm reading a page or an aggregator site in my main Firefox instance and I'm not sure about a link, I can use the context menu's 'Open Link in New Private Window' option and there I go; I can check it out without it being marked as 'visited' and thus 'read' in my history. If I decide that I want to read the page for real, I can re-open the link normally.
(Reading the whole thing in Private Browsing mode is somewhat dangerous, because any links that I follow will themselves be in Private Browsing mode and thus my 'I have read these' history status for them will be lost when I close things down. So I usually switch once I've read enough to know that I want to read this for real.)
In retrospect it's a bit amusing that it took me this long to wake up to this use of Private Browsing. Until now I've spent years ignoring the feature on the grounds that I had other browsers that I used for actual private browsing (ones with far less risk of an information leak in either direction). Even though I was carefully doing things to not record certain web page visits in my main browser's history, using Private Browsing for this never occurred to me, perhaps because I wasn't doing this because I wanted private browsing.
(I think I woke up partly as part of walking away from Chrome , which I sometimes used for such quick peeks.)
One of the gesture actions that Foxy Gestures can do is open links in new private browsing windows, although I don't have a gesture assigned to that action. However I'm not sure I use this enough to make coming up with (and memorizing) a new gesture worth it. And on that note, I wish that you could attach meanings to 'middle-clicking' links with modifier keys held down, so I could make a special variant of middle-clicking do 'open in new private browser window' instead of 'open in new regular browser window'.
(Firefox turns out to have a number of behaviors here, but I'm not sure any of them are clearly documented.)