Check out this subitizing matching set. It has the four types of playing cards (spades, clubs, hearts and diamonds) representing the numbers 2-10 differently. There are different games listed in the pack that you can play with them in math centers or use them as number talks.
Subitizing is a way of instantly counting. In fancy math terms it would be getting to the cardinal number of a set (how many) without without going through the ordinals (counting each one's position). There are two types, perceptual and conceptual. Perceptual is perceiving the number of objects immediately.