Here is a list of everything we know about so far.
http://www.nintendoworldreport.com/news/28176
Many of Mario Kart 7's unlockables are revealed thanks to the Japanese Mario Kart website, along with my playtest earlier this week.
So far, we can reveal tracks from four of the eight cups:
Mushroom: Toad Circuit, Daisy Hills, Cheep Cheep Lagoon, Shy Guy Bazaar
Flower: Wuhu Loop, Mario Circuit, Music Park, Rock Rock Mountain
Shell: N64 Luigi Raceway, GBA Bowser Castle 1, Wii Mushroom Gorge, DS Luigi's Mansion
Banana: N64 Koopa Beach, SNES Mario Circuit 2, Wii Coconut Mall, DS Waluigi Pinball
Other Cups: Star, Special, Leaf, Lightning (DK stage must reside in Star or Special)
Battle Stages: GBA Battle Course 1, N64 Big Doughnut, DS Palm Shore, Honeybee House, Sherbet Rink, Wuhu Town
Drivers: Metal Mario, Lakitu, Mario, Luigi, Peach, Yoshi, Bowser, Donkey Kong, Toad, Koopa Troopa, Daisy, Wario, Rosalina, Shy Guy, Mii, and two more
Items: Super Leaf, Fire Flower, Lucky 7, Mushroom, Triple Mushroom, Golden Mushroom, Green Shell, Triple Green Shell, Red Shell, Triple Red Shell, Blue Shell, Banana, Triple Banana, Blooper, Bullet Bill, Lightning, Super Star, Bob-Omb
Karts: Birthday Girl, Bruiser, Blue Seven, Bolt Buggy, Standard, Cact-X, B-Dash, Yoshi Egg, Bullet Duck, H2O, Banana Buggy, unknown Bee-shaped kart
Wheels: Standard, Slick, Roller, Monster, Mushroom, Wood, Spongy
Gliders: Flower Glider, Peach Parasol, Super Glider, Swooper, Parafoil
Modes: Grand Prix, Time Trial, Balloon Battle, Coin Runners