Unexpected hobby of Zoro: Zoro likes to flip through picture guides of weapons, as well as collected book of bounty heads.
Sanji's name was Naruto!: Originally Sanji was named Naruto. But Naruto started serialization, so he changed his name to Sanji.
Various ideas of Nightmare Luffy: There were ideas such as "polite and serious" Luffy with a side-part hair style. Him taking in shadow of a swordsman to use swords was already decided as well.
Ace's tattoo: Sabo's initial was carved into Ace's tattoo! (duh)
Luffy was terrible at lying even back when he was a little kid! (duh)
Dadan was originally a man: Early design of Dadan, he was a male. He wore a kasa hat, shades, and smoked a pipe.
The pretty lady shown in the pic... is the current Dadan WHEN SHE WAS YOUNG.
http://img823.imageshack.us/i/11dc522353e.jpg/
Ace and Garp's conversation had hidden meaning: Without letting the readers know, they were actually talking about Roger! (duh)
Spooky face on Chopper's head!?: This was originally going to be used in Sky Island, Robin doing a Face Flower on back of Chopper's head. It was way too creepy to be used.
Chopper's early design was a zebra-raindeer that smokes cigar. Holy hell.
Chopper will never fall in love with a human. He can befriend them and respect them, but he won't find them attractive as a mate.
Early Franky: Franky's early designs were slim, tall man who spent much of his life in jail. He could forge weapons, but could not use them.
FRANKY'S SUPER UNDERWEAR HOLDS HIS CRAFTING "TOOLS" AT ALL TIMES.
Usopp and Garp's interaction: Although it was cut due to page limitation, there was a scene originally where Garp and Usopp have a conversation!
Usopp shows his concern about his dad in the Red Hair Pirates, and Garp asks Usopp to take care of his grandson.
Eye-patch pirate will show up later in the series
Early designs: cigar-smoking raindeer as doc, Naruto/Sanji as cook, a skeleton as a musician, a sniper as First Mate, a female navigator, and a swordsman warrior.
Most of these have carried through in the series, but the shipwright was a midget and Franky was a skinny weaponsmith.
http://img175.imageshack.us/i/netaren82702.jpg/