Texas Competitive Mathematics has sample tests and advice on number sense tricks. There is also a forum for discussing problems with others. TCM
Searchable number sense tricks!!! Math Magic
UIL
Math Forum
Mathnerds
Number sense "tricks" Dr. Numsen
Curious Math
Fibonacci sequences will occur on UIL math tests this year! Fibonacci at Math World
Relation of Fibonacci numbers to the Golden Mean Fibonacci and the Golden Mean