Well, at the very least it is likely one of your ancestors conquered the world, so there's always that guy too.
I remember that after X years, anybody who has a living descendant has THE ENTIRE WORLD as their living descendants. How long is X?
Depending on what you're talking about. If you mean the Last Universial Common Ancestor (of multicellular animals), a few hundred million years (or less, I don't know how long before the Cambrian Explosion it lived). If you mean the Eve/Adam of us all, several hundred thousand years, though that's only because we as a species went through a population bottleneck at one point.
I wonder about that. For one thing, Mitochondrial Eve and Y-chromosomal Adam are separated by almost 100 millenia at a minimum according to most estimates. For another, neither of the two appear to correspond to any of the major species-wide population bottlenecks, theorized or otherwise (of which Toba I would cite as the most famous, albeit with the caveat that it itself is still far from well-proven scientifically). Fascinatingly, most-recent analyses on the Y-chromosome suggest that Y-chromosomal Adam may date to the original emergence of anatomically-modern humans. While Mitochondrial Eve is significantly younger, she's still older than most bottlenecks. It's also important to remember that we haven't even finished mapping the mitochondrial DNA or Y-chromosomes of all humans yet; this is how Adam got pushed back so far since the old studies (new archaic Y-chromosomal DNA was discovered during genetic sequencing of Africans, allowing the identification of an earlier common patrilineal ancestor), and it could easily happen to Eve as well. All these two are are the most recent matrilineal and patrilineal (respectively) ancestors.
EDIT: Also, it's worth noting that any most recent common ancestor is not automatically a consequence of a population bottleneck; it's simply an individual who enjoyed significant reproductive success. Dying without having children is simply one way in which this could occur; if the other family trees at any point between now and the present died out or bred into the MRCA's lineage, it would and did occur this way. For instance, the MRCA of most Europeans may date to as recently as the medieval period, and smaller populations can be found to have MRCAs as recently as only 500 years ago.