The search box is drawing from a list of colors. Start typing (try a primary color) to see the dropdown list appear. My blog post describes the implementation of this in detail, but briefly, the red printout beneath this text is a vardump of the post of the form. Using javascript we can extract an additional key from from the data that was selected and store it in a hidden variable. This mimics the traditional key,value distinction in an html select box element. The code also prints a call to rand() just so you can see something change when you submit the page with the same value selected...

Update: Added "Bonus" value in process of testing whether url of server can include GET params. See source (and server source) for details...

array(0) { } 1258709996