ICO

Are we turning this into a general 'What games to show to get (female) nongamers interested in games' thread now?

I'll jump in.

Dwarf Fortress

Mirror's Edge: A female protagonist, interesting world, and aside from a couple of annoying combat moments (not too difficult on easy I think) it's not a very difficult game to play through.

Portal: Another female protagonist, even if you don't see her much. The gameplay is pretty unique too, and fairly easy to grasp.

Half Life 2: Just to get rid of that stupid misconception that all those FPS games consist of nothing but dumb shooting.
If you get the Orange Box you get HL2 and Portal together.

Psychonauts: A colourful world with interesting characters, lots of humour and platformer gameplay. Overall it's not a very difficult game, except for the last levels.

Rayman 3 Hoodlum Havoc: Another nice platformer.

Tales of Monkey Island: It's funny, you can't lose, and doesn't rely on reflexes.

Audiosurf: Ride your music! Awesome. I prefer Beat Hazard but Audiosurf is easier and more relaxing.