Pistol - 45 acp
Battle rifle - .308
General Hunting rifle - 7x64 (I live in Europe)
Special hunting rifle for big pigs - 8.5 x 63 REB, a special caliber that is basically a 7X64 necked up to a .338, or better said for you other Murkans, a little longer 30-06 necked up to a .338.
(And you thought that icon was some sort of secret code.)
Shotgun - 12 guage
General pest (inference intended) elimination - .223
real damn accurate military rifle shooting - 6.5 x 55
cheap blasting caliber at the rage - 9mm
Medium distance shooting (to 500 meters) - 300 winmag
Long range rifle shooting (1,000 meters) - .338 lapua mag
Piss off the guy next to you at the rifle range caliber - 50 BMG
Piss off the guy next to you at the pistol range caliber - 44 mag
Teach your neighborhood pre-teens to shoot caliber - .22 lr
Semi automatic rifle for drive hunts - 9.3 x 62
Favorite caliber to impress the young 35 year old hottie next door with what style and class you have (OK OK, it is the rifle not the caliber, I will admit it) - 9.3 X 74R in a hand made Ferlach side by side exposed hammer double rifle.
Favorite caliber to take to the end of the world as we know it when you can only take 1 rifle - 22 mag in a bolt action rifle. You can fill your pockets with a lot of them, they will do what they are expected to do, and it will allow you to feed and defend yourself.
Favorite caliber to shoot red and fallow deer 8x68S
Favorite caliber to shoot foxes - 22 hornet
Favorite caliber to shoot Roe Deer - 222 remington.
Favorite caliber to shoot M1 Garands - 30-06
Favorite caliber to shoot 1903 springfields - 30-06
Favorite caliber to shoot 30-40 Krags - 30-40
Favorite caliber to shoot Lee Enfields .303
Favorite caliber to shoot mosin nagants - 7.62 x 54 R
Favorite Caliber to shoot wildcatted South America Mausers - 7mm-08
Favorite Caliber to shoot wildcatted German Mausers - 8mm-06
Favorite Caliber to shoot neighbors cats that crap in the driveway 4.5mm airgun