CheatOgre.com: Resident Evil

Ending bonuses:
Successfully complete the game as Jill or Chris and save the game. A new background will appear on the main menu. Select the "Once Again" option when playing your completed saved game. You may now choose new difficulty settings for the replay. You will also get a key that will allow the character that completed the game to have a new costume. Enter the room with the large mirror on the second floor of the mansion. Unlock the door in the back. Enter the closet and move all the way to the end of the rack of clothes. A message asking "There is an outfit that fits you perfectly, do you want to put it on?" will appear. Select "Yes" to change your character's clothes.

Successfully complete the game in once again mode under the normal difficulty setting with a time less than five hours. This unlocks the "Real Survivor" option, the .40 Smith And Wesson gun with unlimited ammunition (replaces the combat knife in a new game), and bonus costumes. If the game was completed using Jill, the bonus costume will be her outfit from Resident Evil 3.

Hint: Checking Zombies:
If you are not sure if a zombie is dead, walk up fairly close to it (but not so close that they start chewing your ankles) and simply back up. If the Zombie is alive, the character will do a wary backup move instead of the standard backup done when there is nothing there.