You could spend a very, very long time playing all the games in the Grand Theft Auto franchise -- not including the older top-down titles and the latest (currently) console-only GTA V. If you have around $10 handy, a bar fridge full of food and drink and a colostomy bag, you could enjoy this, uh, special experience.
Green Man Gaming is offering its "Complete GTA Bundle" for $US12.49, down from the usual price of $US49.99. This is already darn cheap, but as emwearz over at OzBargain notes, if you enter the code "OQE4LG-WEQPSE-SMCME1" during checkout, it'll take off $US2.49, bringing us to the round figure of $US10.
Once purchased, you'll have access to GTA III, Vice City, San Andreas, GTA IV and Episodes From Liberty City. That's a lot of car stealing right there.
Update: So it does actually come with the first two GTAs! Thanks everyone for the tip.