First off, make sure you get D-Fend Reloaded. It's DOSBox plus a slick front-end. Everyone should have this if they want to play old games.
Now, here's some suggestions:
-Alone in the Dark 1 and 2 - Classic RE-style survival horror from France
-Albion - Scifi RPG from Germany
-B.A.T. 2: Koshan Conspiracy - Comic-book styled adventure game
-Betrayal at Krondor - open-world RPG
-BloodNet - Cyberpunk adventure/RPG with vampires
-Colonization - American Revolution-based Civ game [recently remade]
-Dark Seed - HR Giger adventure game
-Dark Sun 2: Wake of the Ravager - D&D RPG
-Death Rally - Top-down racing game with weapons and upgrades
-Master of Magic - Fantasy Civ game, focused more on attacking than diplomacy
-Normality - First-person adventure game, really good
-Relentless 2: Twinsen's Adventure - Isometric action/adventure
-Settlers 2: Gold - City sim with competition against other cities
-Ringworld: Revenge of the Patriarch - Scifi adventure game
-Rise of the Dragon - Cyberpunk adventure game
-Strife - RPG/FPS with an open world
-System Shock - RPG/FPS with a horror bent
-Universe - Scifi adventure game
-Quest for Glory series - RPG/Adventure from Sierra
-One Must Fall 2097 - 2D fighter with upgradeable giant robots