These puzzles look like a lot of fun for whole number and integer arithmetic review. I think they would make a great warm-up at the beginning of a class or math club meeting.
Hat tip: MathPuzzle.com
[Edited to add: The creator of Hexa-Trex, Bogusia Gierus, writes, “I am also a mother (of two really young children) and math teacher in Montreal, Quebec. My hobbies are the same as yours (I love to teach, learn math and anything math related such as play and invent math puzzles).” Check out her web page at www.nucleuslearning.com or her blog here.]
Denise Gaskins' Let's Play Math 