Future_Suture: The Humble Store gives you a DRM free version and a Steam version with a single purchase if both are available. That way you can enjoy Linux gaming both without DRM or through Steam.
ssokolow: ...and
IsThereAnyDeal.com can filter for Linux versions.
They don't seem to be able to filter for DRM-freeness (though, if you know a game is only available with DRM, they can filter for "DRM = Steamworks") but you can limit the effects of that by [url=http://isthereanydeal.com/#/filter:desura,gog,dotemu,shinyloot,humblestore,indiegamestand,gamesrocket,&price/0/5,&cut/50/100,&hidemac,&hideshops,&linux;/option:vouchers]filtering[/url] for the seven stores they track that, whether or not they actually have Linux content currently, are most likely to offer DRM-free versions.
(And the waitlist feature lets you set store filters on a per-game basis so you can exclude known DRM-riddled offerings from consideration.)
Now they just need to start tracking
FireFlower Games,
, and [url=http://www.indievania.com/games?platform=Linux]Indievania so I can bump the number of sites in my filter up to 10.
They will soon start to track FireFlower Games. :)