I think I might've been one of the few people not introduced to 4chan though /b/. I started on /co/ instead. Still frequent it, too. Truth be told, it's one of the site's safest boards. I mean it's still pretty cesspooly, (what with it's frequent Homestuck generals), but otherwise the win-o-threads, drawing threads, storytimes, superhero redesign threads, (and currently the Pacific Rim threads...the hype for that movie on /co/ is an unstoppable freight train of the hypest high) are pretty top notch.
Though, a huge Protip: Never go there when there's a new superhero movie out, they will spoil the fuck out of it before it even comes out in the states/australia.
Also, /v/. /v/. /v/, /v/, /v/. Forward slash. Forward slash.
(I go there quite a bit too. They're exaggerated opinions are hilarious.)