Here's one at KnittingAbout.com. It looks pretty cute!

Fabulous Fulled Hat
Offers some variations. Pictures can be found here and here.

how do I get the directions for a boiled wool hat pattern?

Pattern: http://www.woolworks.org/patterns/fulledhat.txt

Picture (scroll down): http://www.wingedsheep.com/blog/2007/01.html

The only 'trick' is finding a bowl the size of your head.... which is a must if you want the hat to fit.

Not free but Fiber Trends has knit and crochet felted hat patterns. The instructions are for various sizes and are well written. Scroll through the "Accessories" - there are several different hat patterns (the site isn't well organized).

Here is a link that might be useful: Fiber Trends patterns