I'm interested in what games play in a window, preferably turn-based games. I'm looking to play at work (on my lunch hour--what?!?) and a window is much less conspicuous that a 20" monitor with a game running fullscreen.
Thanks

Well, most games can go fullscreen if you force it with 3D Analyse, it's much better than praying it works or not.

I'm pretty sure all DOS based games work in windowed mode. As I recall, most turn based games on GOG are DOS based, so you're in luck there.

DOSbox and(/or?) ScummVM can be configured to run in a window (by editing the ini/conf file for a change in default behaviour, or via [alt+enter] for a temporary change), so the games running under those virtual machines should be fine... Heroes of Might and Magic is one that fits your wishes (being turn based).
To be honest, I'd be surprised if the [url=http://www.gog.com/en/gamecard/chessmaster_9000]chess games couldn't play in a window as well (but don't take my word for it, I haven't actually tried them).