Citi Rewards are a new promotion from December 15, 2010. You can buy the items from Here

Item	Stats	Price
5 Skill Points		500 pts
10 Hired Guns		300 pts
$10 Game Card		1,000 pts
$25 Game Card		2,500 pts
$50 Game Card		5,000 pts
$10 Zynga Card		1,000 pts
$25 Zynga Card		2,500 pts
$50 Zynga Card		5,000 pts
Sleeved Armored Vest	37 81 118	700 pts
Red Rover	38 88 126	900 pts
Puff Adder	35 75 110	500 pts