Hi everyone, I was interested to see that this had been done and that it worked in all browsers without any hacks. My 'experimenting' time is limited because of paying jobs and publishing new demos on CSS play based on known methods.
I did have a few spare hours on Sunday so thought that this might be a challenge.
My version is only a basic fixed width dropdown and is in the early stages of development. It does still require a lot of refining to make it really usable.