Rapture Letters was a Christian website built around the belief that the Rapture is going to happen Any Day Now. It is a free service, offered to those who think they will be taken up (but are actually those most likely to stay behind), designed to clarify the mystery of all the missing people to those poor atheists who've been left behind. It's basically a nice cover-all for those who haven't been that gung-ho when it comes to spreading the word of God to their less religious friends. Now Rapture Letters can give them a big nudge in the ribs, once you're sipping ambrosia with the saints.
They've even got around the "well who sends the mails" question, by having a "dead man's switch" linked to the mailing program, which will immediately send the mails if not reset. The site however is seeming dead as of 12th March 2014, or the owner got raptured without actually making sure the switch is working.
The site offered a sample letter that wannabe Rapture-ites can send to their poor, doomed friends and relatives, which really reads like a smarmy "na-na-nana-na." The basic premise is that the sender is now in Heaven, and if only you'd read and believed the attached Bible verses, you could be picking out your own harp as we speak. It goes on to add that it's not too late to be saved, even though chances are you're going to get the Heaven the hard way by only repenting now.
As of Dec 21, 2013, at the cost of $7 per email recipent you can send your letter on the Friday after the rapture to your left behind loved ones.
Assuming that you're not too busy being engulfed in a lake of fire to read the mail in the first place, chances are that the tone of the letter will leave you feeling relieved that you don't have to spend eternity with those smug bastards.