Steam's offering the previous titles in the Grand Theft Auto series altogether for a fiver or $7.50.
Grand Theft Auto, Grand Theft Auto II, Grand Theft Auto III, Vice City and San Andreas are all in the pack, but there's no GTA IV.
Also worth noting is that the first two GTAs are only available to get with the full bundle.
Do it if you haven't already. You're talking about arguably three of the greatest games of all time within that pack.