My unusual use for Firefox's Private Browsing mode
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.)