I remember a thread here earlier this year where someone was looking for a hat like the Mad Hatter's in Burton's version of Alice. Someone found a little one on a headband that was cute, but some people wanted a full-size one like what was being sold in in the parks, albeit sans the ugly orange hair that was attached.

Well, I just came across this:

Mad Hatter Top Hat - Alice in Wonderland Johnny Depp Mad Hatter Hats