If you plan to do online shopping check out this link first. Register for free and the Feral Cat Spay/Neuter Project ends up getting a donation from the retailers you purchase from!
Here's a great idea for any cat lover on your list - sponsor a kitty for the month at Purrfect Pals with a one time donation of $25 and receive a beautiful card with a photo of the kitty you selected to give to your gift recipient.
If you have people on your list who might prefer to see a gift made in their name to an organization that helps a broader audience than just kitties (such as those who think Heifer International is a worthy group to support), check out Help Animals India. Your donation will go far to support disaster relief, environmental projects, educational efforts, and help individual animals who are suffering as well. This is a top-rated charity of 2012 and you can be sure you are helping humans and animals.