The Chinese believe that the animal ruling the year in which a person is born has a profound influence on personality saying "This is the animal that hides in your heart"
There are 12 animals and so each animal features every twelve years. The following table covers the period 1924-2007

Rat?????? 24?? 36?? 48?? 60?? 72?? 84?? 96
Ox??????? 25?? 37?? 49?? 61?? 73?? 85?? 97
Tiger???? 26?? 38?? 50?? 62?? 74?? 86?? 98
Rabbit???27?? 39?? 51?? 63?? 75?? 87?? 99
Dragon? 28?? 40?? 52?? 64?? 76?? 88?? 00
Snake?? 29?? 41?? 53?? 65?? 77?? 89?? 01
Horse??? 30?? 42?? 54?? 66?? 78?? 90?? 02
Sheep?? 31?? 43?? 55?? 67?? 79?? 91?? 03
Monkey 32?? 44?? 56?? 68?? 80?? 92?? 04
Rooster 33?? 45?? 57?? 69?? 81?? 93?? 05
Dog?????? 34?? 46?? 58?? 70?? 82?? 94?? 06
Boar????? 35?? 47?? 59?? 71?? 83?? 95?? 07

We all know a rat or two, thankfully the occasional tiger, a few snakes, several sheep, the odd cheeky monkey, more dogs than you can shake a stick at, and a few bores. So plenty of inspiration there, then.
No, but seriously, this might be useful for the special birthdays, that is, in 2005,

?????????????????? 18th??? born 1987???Rabbit
???????????????????21st??? born 1984?? Rat?
?????????????????? 30th??? born 1975???Rabbit
?????????????????? 40th??? born 1965???Snake
???????????????????50th??? born 1955???Sheep
?????????????????? 60th??? born 1945???Rooster
?????????????????? 70th????born?1935???Boar
?????????????????? 80th????born 1925?? Ox

The animal could inspire the design on the card front and here's a template verse that could be used

Today, you're (30), born in ('74)
According to Chinese legend, ah so
There's an animal lurking inside you
You're a (tiger), don't ya know


Strictly speaking, it is about the year of birth but?the concept needn't be confined?to just birthday cards. Anniversary cards could use this theme, the year representing the birth of the subject's marriage.??