Steam are having the final days of their Quakecon Pack 2011 sale. It's a monster ID Software pack including all games made on the various Doom / Quake engines:
 
<p style="padding-left: 30px;">Quakecon Pack 2011&nbsp;Includes 34 items: Quake III Arena, Quake IV, Wolfenstein 3D, The Ultimate Doom, Final DOOM, DOOM II, QUAKE, QUAKE II, QUAKE II Mission Pack: The Reckoning, QUAKE II Mission Pack: Ground Zero, QUAKE III: Team Arena, HeXen: Beyond Heretic, HeXen: Deathkings of the Dark Citadel, Heretic: Shadow of the Serpent Riders, Spear of Destiny, Return to Castle Wolfenstein, QUAKE Mission Pack 2: Dissolution of Eternity, QUAKE Mission Pack 1: Scourge of Armagon, DOOM 3, HeXen II, DOOM 3 Resurrection of Evil, Master Levels for Doom II, Commander Keen, Rogue Warrior, The Elder Scrolls III: Morrowind&reg; Game of the Year Edition, Call of Cthulhu&reg;: Dark Corners of the Earth, BRINK, Fallout 3: Game of the Year Edition, Fallout: New Vegas, Hunted: The Demon&rsquo;s Forge&trade;, Fallout New Vegas: Dead Money, Fallout New Vegas: Honest Hearts, Fallout New Vegas: Old World Blues , The Elder Scrolls IV: Oblivion&reg; Game of the Year Edition Deluxe
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That's Fallout 3 + New Vegas + The expansion packs with Morrowind and Oblivion thrown in (and everything else).&nbsp;Given the USD is so cheap right now, it's probably gonna be cheaper to pick this up even if you already have most of them.