Create a Wordpress PLUGIN / WIDGET

A wordpress dropdown search plugin / widget operating like that featured at the top of the homepage of [login to view URL] 1. On the front page there will be a dropdown box with Boat Makes (Boston Whaler, Riviera, Quintrex etc). 2. When you choose a car make, a new dropdown box appears beneath the first one, listing boat models from that selected manufacturer. 3. When you select the car model, the relevant categories are filtered and displayed. (I.e. If Quintrex Boat Brand were selected, then all Quintrex models would be displayed in the second drop down box. When a model is selected all posts related to that model would be filtered and displayed, 4. This must be able to be placed at a widget in a wordpress sidebar