A lot of the games listed on your website are also available for Linux and Mac.

In the vast majority of circumstances the binaries for these versions are floating around the net free of charge (like in the case of ID's titles like Doom 3, or Descent 1 to 3 and a ton of other games usually converted by Loki or other such software houses) but it can be a pain to find them and use them with your special versions.
Often they'll also require DRM to which I cannot comply with, for example the Descent 2 executable requires a CD key.

I know you guys are already extremely busy being nothing short of fucking awesome but... I use Linux mostly. It'd be really nice if my purchases here could at least be used with the real binaries for my platform somehow, or if my platform was supported directly.

*crosses fingers*

A lot of those Loki ports are suffering some serious bit rot these days. Supporting them would be non-trivial. Also, free Linux executables are the exception not the rule (it was mostly an id thing).

Yes, the programs would need some debugging. Probably not too much. Some of the games are ridiculously old and need a lot of patching but none at all. It's the same on Windows though, except worse, so that's a red herring if I've ever seen one, only being even slightly valid due to the relative popularity of the platform - although The Humble Indie Bundle seems to suggest that there are A LOT more Linux users who are desperate for games than one might think.

Here's a good example:
http://www.liflg.org/?catid=6
http://www.liflg.org/?catid=7

:)
But again, some of these require DRM, and this only adresses Linux. I know on Mac it's a completely different story. I didn't say this was going to be exactly easy, but I doubt it will be anywhere near as hard as many, including you, make it out to be.

If you're familiar with Wine you can use that to extract GOG installers; games using DOSBox or ScummVM can be easily played by dropping in the appropriate native files, as can Windows games that have source ports available (e.g. FS2Open for Freespace 2). See the GOGmixes for games using DOSBox and games using ScummVM for games you can use in this manner (I don't think there's a GOGmix for source ports yet, however).

Android is a Linux derivative, give it some time and we will see a market shift to open source architecture powered by a non Microsoft API as more and more become accustomed to developing on a Linux based system and Microsoft helps the process by throttling DirectX advancement to that of their latest XBOX hardware and continues to convert Windows into a slightly more interactive version of the Xbox dashboard.

I only posted because I own most of Loki's games.

Linux is just not a friendly environment for old blobs. It's not even a single OS. Take a look at what you need to do to run some of these old games. Would a non-technical user put up with that? There's so much variation between users that I doubt GOG could shield everyone. GOG generally doesn't even get source to work with.
http://www.swanson.ukfsn.org/loki/

The non-id installers you linked seem to be mostly source ports, based on pirated materials, or reverse engineered engines. GOG sometimes uses scene cracks but come on.

Most Linux users aren't really serious about gaming on the platform (me included). You know Quake 3 Arena (one of the biggest blockbusters the PC has ever had). We got a port of it about 2 weeks after Windows and for a comparable price. It only sold 200 - 500 copies. :( This is not an isolated incident.

http://phoronix.com/forums/showthread.php?23782-It-s-Official-Valve-Releasing-Steam-Source-Engine-For-Linux!&p=174418#post174418

I'm dubious about the Humble Bundles being proof of a market for Linux games. Those bundles always seem to hit Slashdot and the like and have a very public display of platform performance. A Linux user can assuage their guilt for not better supporting the platform by paying a pittance above disinterested Window's users. "Look at how much more we payed for these tired old indie games that every Windows user who was actually interested in already purchased a year or two ago. It's not our fault Loki died, Hyperion dried up, LGP is at death death's door (and implement obnoxious DRM), id & Epic won't give us the time of day, we didn't get NWN2, etc."

Dosbox and WINE work pretty well. Windows is cheap. The number of Linux gamers is small. Old Linux games will not 'just work' for everybody and there really aren't that many of them. More rights will need to be negotiated. It sounds like a lot of trouble.