http://www.artofproblemsolving.com/Wiki/index.php/AMC_8_Problems_and_Solutions
not as good as the above link but still very good math competition problems
http://www.artofproblemsolving.com/Forum/resources.php?c=182&cid=203&sid=54da147e2b4b1005d0d62f86b8642a3c
