The Murder of Roger Ackroyd was the first Agatha Christie book I ever read and it knocked my socks off. Some other books with unreliable narrators I liked are Shutter Island by Dennis Lehane and Patricia Highsmith's The Talented Mr Ripley.
My two favorites are the governess from _The Turn of the Screw_ and Humbert Humbert from _Lolita_. In my certainty that I am right about EVERYTHING, I have very little patience for anyone who claims the governess is meant to be reliable (and there are lots of respectable types who claim just that). And I judge very, very harshly anyone who ever refers to _Lolita_ as a love story, rather than a catalogue of one man's destructive delusions.
Patricia Highsmith does a few like that (little tales of Misogyny has a great one). Confederacy of Dunces? Does that count? Also there's a Swedish crime author who has some one die in the first person - you think they're a new character and then it suddenly stops mid sentence and you turn the page and the police are doing his crime scene (from the other detectives voice). Brilliant!