I'm relatively new to PK Dick, but I can definitely endorse the William Gibson recommendations. Neuromancer is one of my all-time favorites and well worth reading if you enjoy the cyberpunk genre. This is a great thread and I definitely plan to hit the library soon so I can pick up some of the books that have been recommended. Keep 'em coming! Thanks everyone!

My favorite works of PKD are the first two books in the Valis series: V.A.L.I.S. and Divine Invasion. I haven't read the third one (The Transmigration of Timothy Archer), perhaps because the time has not come for it yet.

Divine Invasion is especially cool for a psychedelic mind.