Puzzles
General Puzzles:
Jane Street Puzzle archive
Thanu Padmanabhan's play themes
Misc Puzzles
Gurmeet Manku puzzles page
100 Prisoners Escape Puzzle
Quine Puzzle
The Puzzle Toad
The Riddles
Math is fun puzzles
A Fantastic Geometry Puzzle!
Mind your decisions - Presh Talwalkar
Logic puzzles:
The Hardest Logic Puzzle ever
Other puzzles:
Simon Tatham's Portable Puzzle Collection
Zebra Puzzles
Concept is Puzzles
Pentominoes
Simon Tatham's Puzzles (Browser version)
Puzzle Bridges