Actually it depends. Dubs can be censored due to "inappropriate" references and such depending on who dubs it and where it's released. Subs, or at least fansubs usually don't try to make these references "nation friendly." Also Japan censorship laws are pretty much non-existent outside of pornography.
Dragon Ball through Dragon Ball GT - Aliens that had less than 5 fingers in the manga were given 5 in the anime (with the exception of the Saibaimen). All the Namekians, Dodoria and even Majin Boo's later forms all had less than 5 fingers in the manga. Also, decapitations were made less graphic and sometimes cut out from plain view. #16's head being smashed in was a lot more gruesome.
Dragon Ball Kai - No hole in Goku's or Raditz's chests from Piccolo's Makankosappo, no more Vegeta and ReaCoom giving the middle finger, no more showing Freeza bucking Kuririn around after spearing him with his horn and licking the blood as it drips down his face.
Hunter x Hunter - Quite a number of deaths were altered from the manga, including not showing decapitation.
One Piece - No middle fingers allowed, either. Luffy stabbing himself in the face as a kid, which caused his scar, was also omitted.
Another big no no in other anime is showing underage kids smoking or drinking. Which is why we don't see Sanji taking up smoking as a kid, or Yusuke from YuYu Hakusho smoking in the anime.