There's been quite a few threads about specific games in ScummVM and ResidualVM, but never one all-encompassing thread, so I figured I'd make one since ScummVM and ResidualVM are ever-evolving. :)
I'm a huge fan of the 2D adventure game program ScummVM and it's sister project for 3D adventures, ResidualVM (and the sister project ScummVM-Misc which includes an engine for text adventures made with Inform) by extension. So much so that I actually prefer to play adventure games through these programs. :)
I enjoy testing out engines as they're WIP, and there's often some times when the engines play straight through to completion long before they're added to a stable release. I'm playing through Gabriel Knight: Sins of the Fathers in ScummVM right now, and it works really well despite being WIP, and I played through Grim Fandango in ResidualVM before it received a stable release.
I've played ScummVM on Windows, Mac, Linux, BeOS, GP32, Dreamcast, Wii, and iPad and ResidualVM on Windows, Mac, and Linux. :D