The Battle of Midway was an intellegence victory in many ways. The Japanese were not expecting to face the force they did at Midway, and suffered heavily because of it. The four carriers lost were never replaced.
After Pearl Harbor, an essential victory for the American forces and the American psyche.
Thanks.
EDIT: For those interested, more on the role of intelligence at Midway. This passage does not adequately describe the breaking of Japanese code, which is a fascinating subject. The breaking of JN-25 led to everything from special operations missions to assassinations of Japanese leadership. An interesting study on both how code is broken and the implications of doing so.
here's a very basic overview:
http://216.65.20.88/midway/bill_price_2.html