Usopp: Africa (I don't know why he hasn't a specific country)
Franky: America (meaning USA)
Brook: White and black
Nami: Orange and money
Sanji: Seafood and cigarrete smoke
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.
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~