While wandering the NYC offices of my publisher Tor, I happened upon these beautiful 2010 omnibus reissues of Philip Jose Farmer's Riverworld books. These are some of my favorite books of all time, and these editions are fab. Here's the setup, courtesy of Wikipedia:

The story of Riverworld begins when almost the whole of humanity, from the time of the first homo sapiens through to the early 21st century, is simultaneously resurrected along the banks of the river. The number of people is given as "thirty-six billion, six million, nine thousand, six hundred and thirty-seven" (36,006,009,637). Of these, at least 20% are from the 20th century, due to the high levels of population in later centuries compared to earlier ones. There is also a cut-off point, as no one from the 21st century or later is resurrected. Originally the specific cut-off year was given as 1983 (which was still a speculative date when the novels were first published) but this was later updated to 2008. The ostensible reason for the cut-off was that it indicated the point at which most of the human race had been purposefully annihilated during a catastrophic first contact with aliens visiting Earth. The protagonists later find out this is a creative fiction, produced by the masterminds behind the resurrection, so the spies among the resurrectees could identify each other.

Riverworld