*Raises the left fist*
Dual-booting the best Linux (Arch) and Windows 7 (Sadly). After running Mint to get used to Linux before switching to a faster and more custom built System. I've actually migrated everything to Linux except a very few games (like Rayman 2). Of course, a Windows 7 system is quite useful fpr LAN-Parties where a quick install is needed to get going, but everything that I have I try to run on Linux.
That means all Dosbox and Scummvm games, and native ones (UT, UT2004, 0ad, World of Goo, Freespace 2 and Neverwinter nights). Everything else I run through wine + playonlinux, which works like a charm, especially thanks to the GOG-Install Scripts from a user here. (Thanks Petchema! )
Personally I'd like to see the native versions from Indie Developers here (Trine, etc) and tar.gz archives of the Dosbox games, so we don't need to run the Installer in Wine. That would ease Installing Dosbox games.
A GNU/Linux and Mac section would be nice, although game specific Linux info should stay in the games own subforum.