From the braggadocio files: NYPD are now regularly monitoring Facebook, MySpace, Twitter and YouTube to try to catch big-mouthed criminals who like to brag about their illegal activities. They caught Manhattan thief James Roberts that way; he boasted about his new bling on MySpace days after mugging a man at a Chelsea bus stop, and even put pictures up wearing the watch and ring he stole. Police called Facebook "instrumental" in busting up a ring of drug dealers who sold coke, ecstasy and dope at nightclubs like Rebel and the Roseland Ballroom last year, and gangs regularly have their own MySpace pages with easy-to-identify pictures. "It's almost become unfair. Facebook and MySpace are killing these guys," said one law-enforcement source.