If you're a big fan of 2D adventure games like Secret of Monkey Island and Broken Sword, then you probably know of SCUMMVM which is an emulator to play those games.
But if you're wondering how to play later games like Grim Fandango and Escape from Monkey Island which use a 3D engine called GrimE you'll need to use a spin-off of the SCUMMVM project, Residual.
Residual's aim is to emulate the GrimE engine so those games can be played on modern systems. They've just obtained their own site so keep a close eye on it. Hopefully you'll soon be able to play Grim Fandango and Escape from Monkey Island the way it should be.