I like to fold many of these T-shirts at once and store them in a small packet, ready for use in cards. I'd sometimes pair them with other pieces eg. pants to create a entire ensemble. Magazines, comics and all kinds of interesting paper make great T-shirts that you can use to suit the personality of the recipient. These cards are perfect for males like Dad, Grandpa, uncles, brothers or teachers (I don't know about you, but I find it much harder to make cards for guys than girls).
Thanks for looking. Hope this post has been useful.