Integer websites

http://www.ixl.com/math/grade-7 scroll down to Operations with integers and attempt word problems and subtraction.

http://my.hrw.com/math06_07/nsmedia/tools/Integer_Chips/Integer_Chips.html

use these if you have no counters to solve problems

http://www.bbc.co.uk/bitesize/ks2/maths/number/negative_numbers/play/

http://nlvm.usu.edu/en/nav/grade_g_3.html