The Nike Football site uses a deceptively simple trick to draw attention to its unobtrusive search box. The narrow sidebar navigation menu features what looks like a search box that is a bit too small to be usable. Clicking what you think is the search box expands a real search input adjacent to the sidebar in the body.

It's a clever method, but as you can see from the comments, it's not without problems. A good example of how simple solutions aren't always easy to come by.