What would interest you: games, utilities, information, or what?
FWIW here's some good puzzle games. Most have free limited sampler versions.
Aqueduct - a sliding block/pipeline making puzzle
Cut The Rope - a physics puzzle
Isoball - a ball run creation puzzle
Magnetic Block Puzzle - as on clickmazes.com
Myst - the classic graphics adventure
Riven - the first sequel to Myst
Trainyard - draw tracks to get trains to their destinations