Westwood (now Petroglyph) and Square (-Enix) come to mind as possibilities for this post. Singletrac is the big winner though. These guys made most of the vehicular combat games I played on PlayStation (Twisted Metal 1&2, Critical Depth, Rogue Trip). I also played some of their other games, like Warhawk and Jet Moto. That group would later become Incognito, who would resume the Twisted Metal series and make the PS3 Warhawk. That group would later become Eat Sleep Play and Lightbox Interactive, making more Twisted Metal and the recently released Starhawk.