Search for free tutorials on drop down boxes or dhtml (dynamic html) sites and search their archives.
Most of the time the drop down boxes use a form tag unless you want them to be java script. And java is one thing I don't know a lot about.
I'm sure you'll find something suitable looking on those tutorial sites.
*didn't realize how old this thread was*
Hopefully you found it.
Illustrator CS, Photoshop 7, Blender 2.46, Nikon D40