Ted Bundy: "The Only Living Witness" by Stephen Michaud and Hugh Aynesworth. Of the many books about Ted, this is by far the best and most comprehensive. Along with this you may wish to read "Conversations with a Killer" by the same authors, which are transcripts of their interviews with Bundy, where he talks about the kind of person who would have committed the crimes (sort of his version of OJ's "If I Did It.") A riveting, incredible account of America's quintessential serial killer.
Of the other Bundy books, Ann Rule's "The Stranger Beside Me" is pretty good given her background as a crime writer and insights into criminals (she worked with Bundy on a suicide hotline in the late 60s), and if you find it, "My Phantom Prince" by Patricia Kendall(?) is the POV of Bundy's fiancee during the later years of his predations, an interesting account of how it feels to discover your lover is one of America's greatest annihilators of women.
Robert Keppel was the Seattle detective who hunted Bundy for his Washington murders, and was later tasked with hunting the Green River Killer. In 1984, Bundy contacted Keppel and offered to provide his services in helping him profile the GRK, and Keppel wrote "The Riverman" about this 'collaboration'.
"Angel of Darkness" by Dennis McDougal is the story of gay freeway killer Randy Kraft, who was eventually convicted of 16 murders but had a 'scorecard' that investigators believe meant he had murdered 67 or so young men. The book also covers the other California freeway killers of the time, Bill Bonin and Pat Kearney. One of my top five favorite books about serial killers.
Edmund Kemper is one of my favorite murderers. 6' 9" tall, extremely smart and personable, he shot his grandparents at age 15, and then dissected a half-dozen coeds in his 20s before finally turning his wrath at the person he hated most. Margaret Cheney wrote "Why: The Serial Killer in America" about Kemper, and it's a terrific account of the case. It also covers the other two maniacs at work in Santa Cruz at the time, schizophrenic serial killer Herbert Mullin and mass murderer John Linley Frazier.
Phil posted "Deviant" by Harold Schechter, which covers Ed Gein. Schechter also wrote "Deranged" (about sadomasochistic serial child killer and cannibal Albert Fish) and "Depraved" (H.H. Holmes, the subject of the aforementioned and excellent "Devil in the White City"). Excellent books, all.
The best book on John Wayne Gacy is "Buried Dreams" by Tim Cahill, and the best book on Jeffrey Dahmer is "Jeffrey Dahmer" by Dr. Joel Norris. Similar to Dahmer (and predating him by 20 years) is Dennis Nilsen, the British man who murdered 15 men because he was lonely, the definitive accoint of his crimes being "Killing For Company" by Dennis Masters.
On the detection/profiling end, the aforementioned books by John Douglas are great, but let me recommend "Whoever Fights Monsters" by Robert Ressler. Ressler was Douglas' FBI partner, and with him pioneered profiling and behavioral science.
That should keep you busy for a while.