Why? If the connection is being MITMd, then both sides need to be able to figure this out.
There was a long discussion on this (regrettably rejected by the browser vendor) to allow the SSL fingerprint to be obtained in JS. That would make it reasonably easy for the site operator to verify that the SSL cert hadn't been tampered with. (Of course, a really evil proxy can scan for the JS, but that game of whack-a-mole is usually easier for the good guys to win, at least sometimes).

As a website operator, I want to know if my content is being MITMd en route to the user. I know about the SSL fingerprint trick that lets a really technical user discover proxying, but I want to automate this process server-side, and stick up a big banner to say "Your employer is snooping on this connection, please log in from a trusted machine" (and then I'll prevent the user from logging in).

I've never understood why we can't get the window-manager and the application to play nice, and share one bar. Usually, there's plenty of space horizontally, and too little vertically. So, why not have the combination of:
[icon] File Edit View History Bookmarks Tools Help ....... "The window title goes here" ....... _ [] X

Of course . but the consumer could then have their favourite OS and phone. For example, I might like a Nokia running Android, while somone else might prefer an S5 with Windows. (What I really want is an iPad with Lubuntu).

But a dual-boot phone, especially if it shipped with both would be widely liked, I think.

True, but how many consumers would like a phone that can run their choice of OS? I certainly would.
If necessary, I'd even pay for MS as long as I don't have to use it. (as with almost all laptops)

If I can get a high-end Lumia and have Android, that would be amazing.

I've found twice now that, on reporting stolen devices (to the UK police), even if we know exactly where they are (trackers, phone home etc), there's no way to get the police to react (promptly) to go and get it back. If the police would quickly go and retrieve stolen devices, the problem would vanish.

Specifically, can we assume that any extension loaded into Firefox via the official extensions repository, is open-source, and that someone from Mozilla is checking the extension before an update is released?

I looked at this, and there are 2 things I can't understand:

1. How does key distribution work? Even public-key crypto of this type doesn't necessarily work if there is a man in the middle.
2. How is metadata protected? For an SMS, often the timestamp and sender/recipient pairing is as revealing as the message content.

For Linux users, is there any way to replace the iTunes functionality to get music and photos onto an iDevice, and have it properly recognise the library?
I only use Linux, but have an iPad3. I have mediocre photo functionality[1] via a jailbreak, but am still stuck with only one folder and no sub-folders. As for getting music on there (especially .ogg), forget it.
[1] http://www.richardneill.org/stotbig#ipad

I agree. Clementine just works, and stays out of your way otherwise. It responds quickly to external changes to the library (using inotify).
For me, my music collection is a set of well-ordered files/directories, each with a .m3u playlist and appropriate tags. (The Unix "everything is a file" approach works well here). Then the music player is just for playback, for playing them, and not for editing tags (use easytag), ripping CDs (a shell-script), nor for buying music (CD store).

If we're talking about the great firewall of china, you're right. BUT most corporate proxies run fairly standard software, and only update it every few months (if that). So, there's a pretty good chance of my getting the JS through the first time, and of the vendor taking a long time to work around it (if they ever do). Yes it's cat and mouse, but there are a lot of mice with different strategies, the cat isn't very quick, and as long as the mouse gets through once, it's enough to let the user know he's being snooped on.

Hashing it won't help - I want to inform the user that their data is being intercepted, not that it's being corrupted.

I operate a webserver, and I'd like to protect my users against SSL proxying. At the moment, all I can do is tell them to check my key's fingerprint against what the browser shows. But I'd really like to do this in JS. Is there any way to use JS to get the fingerprint string (that I can see by clicking on the padlock icon)? Then I could send that back to the server (from JS), and check if it's been tampered.

(A really effective evil proxy would be able to defeat this, but most corporate proxys aren't going to be able to parse my own JS and work out precisely how to transparently defeat it).