Games

Logic

Rush Hour
Sudoku
Solitaire Chess

Board Games

Family Math - a book of games that can be easily set up at home
Math Games and Activities From Around the World - a book of ... well, the title is self-explanatory

Skills Practice Games

Number Twister - http://unschoolingmath.blogspot.ca/2012/03/number-twister.html
Integer Beans
Card Games

• War (can be modified to use addition or multiplication in the "war" part)
• Add to X Memory
• Add to X Go Fish

Descartes' Cove - http://cty.jhu.edu/descartes/explore/index.html

Video Games

Sum Dog - sumdog.com