For those of you who want to test your might at any moment, no matter where you are, Amazon has a deal to help you out. Right now, if you purchase the Wi-Fi model of the PS Vita, you'll get a free copy of Mortal Kombat, along with a 4GB memory card – which will hold you over just fine until you order a more reasonably-sized card.
Mortal Kombat seems like an odd choice for a console pack-in, given its status as both a port and a super-gross violent game, but it is at least a good game! Prospective Vita owners have not always been so fortunate.