As of today (6/13/08), Threadspotting features a Left Behind business that will send automatic emails to your left behind loved ones (or enemies, or co-workers) in the event of the Rapture. You can arrange to send them encouraging messages to help them through the times ahead and increase their chances of getting to heaven. The possibility of gloating that you made it and they didn’t isn’t mentioned, nor is the possibility that the Rapture could happen without you.
Have there been other business models based on the impending Rapture? I vaguely remember something about taking care of your dog after you’re gone, but that might have been a suggested business rather than an actual one.
I’d search, but I can’t think of a keyword that wouldn’t bring up hundreds of unrelated threads.