DOSBOx has been ported to both Linux and MacOS. The games you play with it look and feel the same on each platform.
Macintosh Garden is a site with MAC-only abandonware. There's bound to be some Mac-emulators to play these games on Linux and XP as well.
As for Linux abandonware: Since commercial games for Linux have only been on sale for the last couple of years I doubt you'd find anything. The Linux community is however very good at creating remakes, ports and free version of most cool games, such as
Abuse and
Doom