You've probably seen fancy search boxes before (like the one on the jQuery API) where they have a clickable search icon that appears over the textbox. How can I semantically achieve this effect?
I have seen on some custom Google Search textboxes that it uses a background image on the textbox, and then it receives focus and removes the image. Also, the search box here on StackOverflow appears to also be using a background image of a little search icon. I know how to do that, it is easy, but it's not really the effect I want. I'd like to have a clickable icon that lights up on hover and submits the form when clicked.