All hypothetical…
Let’s say I want to keep track of a list of people and whether they are still alive. Is there an easy way to do this? Are there databases I can periodically query? How much would it cost per person?
If it helps, we can make the following limitations: US citizens, valid SSN, adults only, non-celebrities (normal people).
Other than that, they are all random people; not people I know.
The Social Security Death Index is a good place to start. I caution that it’s often wonky and incomplete, but I have found people I was looking for there.
If SSDI fails, try going to your local library and asking to use Lexis-Nexis address search, typing in the last known address of the person you’re looking for. If they’re no longer alive, they should be red-flagged as “deceased.”
That ought to get you a head start, anyway.
There’s usually a two-month lag before a dead person appears in the Social Security Death Index. The index now includes about 95% of all people who die in the U.S. (The other 5% include illegal aliens, infants, and those covered under federal employee retirement programs.)
More recent is the United States Obituary Collection, at Ancestry.com, which scours hundreds of newspapers daily. Its index is currently updated to February 7, 2009.
Many public libraries have subscriptions to Ancestry.com.
I’ve used this, but the problem with the Obituary Collection is that fewer and fewer people who die have obituaries in the newspaper. If you die in a big city, you’re only going to get your obit in the big-city newspaper if your family pays for it, or if you’re a big shot. The small-town papers are starting to charge for obits too. And of course if the family doesn’t want the obit in the paper, it’s not going to be there.
I’d still take a shot at Ancestry.com, but it’s not going to be nearly as complete as Lexis-Nexis or another public-records aggregate site.
If you are going to rely on “public records”, you’re going to miss entire “closed record” states (e.g., Pennsylvania, Arizona) that do not publish their death indexes; and for those states that do, you might as well wait for the death to appear in the Social Security Death Index first, because it will be faster.
The thinking is that if you show a date of burial ,crooks will break into your home feeling sure nobody is home. I do not know if it is true, but I have heard it several times.
True that. I do most of my work here in New York state and I forget sometimes that other states have more restrictive public record policies.
Thinking of starting a tontine?
Poke them with a sharp, pointy stick 
check their pulse
Press on their thumbnail. It will go white while you are applying pressure. If it stays white when you remove the pressure, they’re probably dead.
But you wanted to know if they’re alive. Okay, if the normal color returns to the thumbnail, they’re likely alive.
Dangit. Looks like I got here late.
slowly backs away, sheathes pointy stick
Can they fog a mirror? 
The SS Death Index is really off for older people. I found my mother’s death is wrong, my grandparents aren’t listed at all, I used to have a neighbor and her son is in there but she is not, I went to both their funerals.
I found one in the death index in 2007 and she died in 1995, so it took a long time to get her in there.
All these people were pretty old. I reckon my Mum and other releatives are due to the fact they immigrated to America and used an Americanized version of their names. Back then you could get as many SS# as you wanted and they nobody was too picky about the name you used.
So if you can’t find somene in the SS death index, you may want to try using alternate spellings of names
It seems the SSDI meets my requirements considering I am not interested in finding out when previously living people died, but instead when currently living people eventually die. The USOC looks interesting too.
Thanks for the help!
A person will be in the Death Master File only if (1) he or she had a Social Security number, and (2) the death was reported to the Social Security Administration.
Research published by the Social Security Administration in 2002 suggests that for most years since 1973, 93 percent to 96 percent of deaths of individuals aged 65 or older were included in the DMF.
Is that some sort of new geek religion ? When you die, your soul bits go to the Death Master File to enjoy the eternal T1 line of Celestial Counterstrike ?
The Death Master File is a database kept by the Social Security Administration. It is known commercially as the Social Security Death Index.
It would appear that the OP has gotten a decent answer, but I’d like to add this.
My high school class, in addition to those periodic reunion sorts of things, sends out an occasional list of classmates no longer with us. I believe the list is maintained by one of the class officers who has always been on good terms with most of the people in the class. Folks would make it a point of letting her know of deaths. She would also make it her business to do some checking on her own.
I have no idea of how she gets the data, but I do know it’s better than anything I have been able to do online. Now and then I’ll try to search for people in school with me (even grammar school people) on Google or Yahoo! but it’s only when something really serious happened to them that I’ll find evidence that they died. It’s easier to find out that they made the news for other things. One guy shot and killed a hunting buddy and that’s all I could see about him.
I appreciate the good responses in this thread, and have laughed at the non-serious ones, and I may be trying to use some of those sources to get data on my chums, if it applies.
Let us know of your successes, please, CaveMike.