Hi, the submitter here.
Of course, I was expecting some "I would ask Slashdot" (Funny:5) and "I would not tell Slashdot" (Insightful: 5) answers but I think that a good procedure could be exposed to the public much like a public encryption key and still preserve the effectiveness.
It's quite interesting to read the 440+ comments and see there's a pattern (or antipattern). I gave 5-6 pieces of contextual data but there are two of them that are being neglected in some way. I said "you are able to speak one language apart from good English" but nobody took advantage of that, interesting. I also said "in a G8 country of your choosing" but I might well have just asked for US citizens (there are some honorable exceptions, true). The "computer savvy" clue was either ignored or überused.
The family ties are the most disturbing (or lets say annoying) to me. Just picture your husband/wife not knowing why you're missing, defaulting to Defcon 1 and going to the police. You want to avoid that at all costs but "they" might be monitoring her. That's why I think this Ask Slashdot should introduce a procedure in your lifes (as we do have at home and, btw, my wife was the one to suggest me to Ask Slashdot) so you have a code, something that sends either one of these two messages to your AAA relative: "I'm OK, just wait and I'll contact you again though it might take time" or "I'm not OK, open the red envelope and follow instructions". Note that those messages can be delivered without saying that as long as you have prearranged them.
The other thing is the money. I think, because this is RealWorld(tm) and not MatrixWorld(tm), you could try and get some cash from your bank but only in T.LT.2h. It's dangerous but not because of the "there's being a problem with your order, Sir, please wait here a couple of minutes" death sentence but for having entered a difficult to escape place (so you should devise a plan to get safely out of the bank).
I loved when in a previous Ask Slashdot about migrating to a country someone said Australia could be a good place to be in in the event of a IIIWW, this is geek-style thinking.
I too remember a guy I was interviewing for a job post in my company that had a plan in case of a zombi apocalypse. It was very detailed (not just the Cardio rule) and I nearly got him on board just for that but, alas, his FOSS knowledge was below par. Well, the main difference between a zombi apocalypse and my setting is that in the latter the world keeps going on as usual and you can't trust other "fellow" humans, but the point is that you can still prepare you way out just in case.
The core of the problem is that you didn't plan this in advance because, not surprisingly, you weren't expecting it but you're forced to devise a semiprofessional plan in hours time.
I'll post my own answer in a few hours time so you can be sure I'm not cheating here.