I'm not sure how well-known this series is, but I really enjoyed it. The entire series is written in first-person perspective and it has a fun dark humor to it.
Synopsis of the first book:
In the near future, the only thing growing faster than the criminal population is the Electric Church, a new religion founded by a mysterious man named Dennis Squalor. The Church preaches that life is too brief to contemplate the mysteries of the universe: eternity is required. In order to achieve this, the converted become Monks -- cyborgs with human brains, enhanced robotic bodies, and virtually unlimited life spans.
Enter Avery Cates, a dangerous criminal known as the best killer-for-hire around. The authorities have a special mission in mind for Cates: assassinate Dennis Squalor. But for Cates, the assignment will be the most dangerous job he's ever undertaken -- and it may well be his last.
