Buy cards in bulk
I like to send cards in the mail to people I don't see that often to let them know I'm thinking of them.
When I see cards I like (Marion Heath is one of my faves) I'll buy a bunch for different people and occasions. When I have the time I write them out and set them aside for mailing.
Cards can be expensive, so I also troll the section where they have the cheapo cards for 99 cents. I know my friends don't care how much I've spent ... they know I'm generous in other ways!