I don't know why but I always get a huge kick out of reading an older sci-fi story that was set in the near future, but it's a date I've lived through. In 2001, I'd just randomly shout, "Kubrick and Clarke were wrong,! We don't have bases on the moon! Those fools!" This is another one where Phil didn't exactly nail 1992 writing in 1969, but it's still a pretty good story. 
 In this 1992, there are people with psionic powers like telepathy or precognition that are used for industrial sabotage, and rival firms are hired to stop it. The dead can be kept in a half-life state and can have limited communication with the living. 
 Joe Chip is a tester for Glen Runcitor's anti-psi security firm, and when a job with a team of Runcitor employees goes horribly wrong, Joe finds reality shifting around him and is soon unable to distinguish past from present and what's real from what isn't. The only constant thing are ads telling him to try the wonderful product Ubik. 
 This is Philip K. doing his usual mind-bending thing, but this time instead of just questioning identity or memory, he's questioning the nature of reality itself. A little dated, but pretty good stuff with a lot of dark humor, which is something there isn't enough of in sci-fi.