Re: A thought on regenerations (spoilers for "Night/Day of the Doctor"
If you wan an original regeneration (me included), how about a stab wound.

Killed in an explosion would be fun.
It would have to be mortally wounded in an explosion. If a Time Lord is killed instantly, there'd be no time for regeneration to kick in. So it couldn't be too big an explosion.
I imagine finding and freeing Gallifrey would be more than enough cause to reward the Doctor with additional regenerations. (Not sure why that's not the obvious answer, since that's pretty much what the show is going to be focused on for a while.)
Well, isn't that just why it doesn't work? If the news reports are true, then the Doctor is currently on his last life, and will need to get a new regeneration cycle
now, or rather two weeks from now. And the search for Gallifrey is most likely going to take a while to pay off, maybe drag on for years. It's not going to be resolved in "The Time of the Doctor." So unless Moffat's been lying to the newspapers and Smith is still just the 12th incarnation, then new regenerations are not going to be a reward for finding Gallifrey.
And maybe the reason people aren't embracing it as the answer is that it's
too obvious, too simple, not interesting enough.
Getting back to the thread's original focus of listing/codifying the properties of past regenerations: A comment in another thread has gotten me wondering how many of the Doctor's prior regenerations were foreshadowed, how many he knew/expected were coming.
1: The First Doctor was ill throughout "The Tenth Planet," so he may have suspected that he was nearing the end of his life. (This is largely because Hartnell himself was so ill and had to sit out much of the story.)
2: The Second Doctor had no warning that the Time Lords would regenerate him (or "change his appearance"). Although it could be said that when he contacted the Time Lords for help, there was reason to expect it would have
some consequences.
3: The Third Doctor chose to confront the Spider Queen knowing full well that the radiation would be almost certainly fatal. He didn't expect to survive.
4: The Fourth Doctor knew the end was coming because of his communication with the Watcher.
5: The Fifth Doctor was aware that he was dying from spectrox toxaemia for at least half the story, although he was searching for a cure. At the end, he chose to give the only surviving dose of antidote to Peri, knowingly sacrificing his life (and unsure if he'd regenerate).
6: No warning whatsoever -- just a sudden crash and Sylvester McCoy in a curly wig.
7: The Seventh Doctor had no warning when he was shot, although he did try to warn Grace what would happen if she operated. Still, I'd say that overall he had no expectation that it was coming.
8: The Eighth Doctor's end came rather suddenly, since it was a short minisode. But the Sisterhood of Karn revived him and gave him four minutes to come to terms with, and choose the form of, his impending regeneration.
9: The War Doctor was not expecting to regenerate, although he realized he shouldn't have been surprised at his age.
10: The Ninth Doctor chose to take the vortex energies inside him to save Rose. He knew he'd regenerate, but he only had a few moments to deal with the knowledge. So it was pretty sudden overall.
11: Oh, just for the heck of it, let's count the Metacrisis: There was no warning before the Doctor was shot (well, grazed) by a Dalek.
12: Oy, was there ever advance warning. A repeated prophecy made the Doctor very aware that his end was nigh, and he had plenty of time to get maudlin about it. Plus he lingered for quite some time.
13: The Doctor's known for a while that he'd die in the Battle of Trenzalore, though he hasn't known when. I assume he'll have a fair amount of advance warning once he finds himself participating in that battle.
So I'd say that only a few of the regenerations have been significantly foreshadowed. The majority have been sprung on the Doctor rather suddenly.