One Piece Fun Facts

Nationality

Luffy: Brazil
Zoro: Japan
Nami: Sweden
Usopp: Africa (I don't know why he hasn't a specific country)
Sanji: France
Robin: Russia
Chopper: Canada
Franky: America (meaning USA)
Brook: Austria

Animal
Luffy: Monkey
Zoro: Shark
Nami: Cat
Usopp: Armadillo
Sanji: Duck
Robin: Crane
Chopper: ...Duh~!!!
Franky: Bull
Brook: Horse

Color
Luffy: Red
Zoro: Green
Nami: Orange
Usopp: Yellow
Sanji: Blue
Robin: Purple
Chopper: Pink
Franky: Cyan
Brook: White and black

Smell
Luffy: Meat
Zoro: Japan
Nami: Orange and money
Usopp: Gunpowder
Sanji: Seafood and cigarrete smoke
Robin: Flower
Chopper: ?
Franky: Cola
Brook: Tea

Age
Luffy: 17 (May 5)
Zoro: 19 (Nov 11)
Nami: 18 (July 3)
Usopp: 17 (Apr 1)
Sanji: 19 (Mar 2)
Robin: 28 (Feb 6)
Chopper: 14 (Dec 25)
Franky: 34 (Mar 9)
Brook: 88 (Apr 3)

Every Straw Hat member also has some sort of marking or item of clothing on their left side.

Luffy: A scar under his eye; a glass armband (really Captain John's treasure map) at the end of Thriller Bark until given to Buggy in Impel Down.
Zoro: 3 earings on his ear, and his black bandana tied around his upper arm when not fighting seriously.
Nami: A tattoo of a mikan and pinwheel on her shoulder, a bracelet Nojiko gave her and a Log Pose on her wrist.
Usopp: A white and blue striped sweatband on his forearm.
Sanji: His eye is covered by his hair.
Chopper: His antler was broken off and reattached with a metal plate.
Robin: Sometimes wears a bangle on her upper arm.
Franky: His arm has a built-in shield and firearms.
Brook: His suits' arm and leg have holes. While alive, he had beads hanging on the side of his sunglasses.

Favorite Food

Luffy: Meat
Zoro: White rice, sea king meat, and anything that compliments ale
Nami: Mainly tangerines as well as other kinds of fruit
Usopp: Pike from an autumn island as well as other fish of the season, hates mushrooms
Sanji: Spicy seafood pasta and food that compliments black tea
Chopper: Cotton candy, chocolate and other sweet food and drink
Robin: Sandwiches, cakes that aren't too sweet and food that compliments coffee
Franky: Hamburgers, french fries and food that compliments cola
Brook: Tea and takoyaki

Wanna know more? C'mere at One Piece Wikia~

Their ealier pic before joining Straw Hats