Card Games
- Blink! (Named Blink because the game goes that fast. Match the pattern, color, or number.)
- Set (Slower, deeper thinking, and just as addictive.)
- Spot It (Not a math game, but a love of card and board games is likely to spill over into math. And when you eventually ask yourself how the heck they made the cards work out, you'll end up doing some serious math!))
Board Games
- Blokus (Helps build spatial reasoning skills.)
- Katamino (Turns pentomino puzzles into a two-person game, and provides a wealth of puzzles from simple to the original killer puzzle - put all 12 pieces into a rectangle.)
- Quarto (Get four in a row, without giving your opponent a winning piece.)
- Connect Four
- Don't forget chess and go
- Our favorite non-mathy board games include Dizios and FlipOut
- Make your own board game...
Puzzles
- Tangrams (Tangoes makes a nice set.)
- Shut the Box (Looks boring to me, but kids love it.)
- Rush Hour (Get the red car out of the lot. These are such fun logic puzzles.)
- Chocolate Fix (The realistic candies add to the fun of these logic puzzles.)
- Perplexus (More coordination than math, and yet... Visualizing what the next rotation will do, before doing it. That's the math. Yeah.)
Building Toys
- Citi Blocs (aka Kapla blocks or Keva blocks)
- Polydrons
- Origami
Instructional Games
- Math Card War (free, uses playing cards)
- Equate (board game, plays like Scrabble, using numbers and operations)
- Prime Climb
Online Games & Apps
- Bloxorz
- Solitaire on a Circle
- DragonBox
- Ko's Journey
- Game About Squares
- Pen & paper games
John Golden's Games page is much more comprehensive.