I'd forgotten temperature because I only work in Celsius. I have no idea whatsoever about Fahrenheit - I couldn't even take a guess at some comparisons.
The -F is there to impress your friends! I know my friends are always impressed when I tell them it was -36F a couple times when we lived in ND. That was rude.
I want time to be both metric and global (i.e. no time zones).
Coordinating with foreigners is a fucking chore.
(Though I do agree with Jon that imperial units are often more ergonomic and thus better for ad hoc reckoning. Naturally, really, since they mostly evolved from body part dimensions. But yes we've been here a zillion times).
Though I managed to get some work from someone quicker yesterday because they didn't realise we were working to a deadline in EST. Though the fucker still only sent through the stuff 2 minutes before the "deadline", good job I didn't tell him the truth.
But nay, I reckon we should have Imperial Time. Yes definitely everyone on the same time, no zones, all Her Maj's GMT all the time. But measured in a happy mix of fathoms, gallons and bushels.
Moving from GMT (or UCT if you insist) would cause too much confusion globally. Even Swatch time had to have a common reference point, although they conveniently moved it to their HQ.
I like Milko's proposal. Speed should be measured in furlongs per fortnight.