did you see Mia's article with the bamboo bracelets? they are technically wood - not sure if it's what you're looking for though
http://www.stylethread.com/columns/columns_feb/offthebeatenpath_feb.html
Here are some, they come in both size small and medium, so maybe they would work.
http://www.calliopeboutique.com/shopexd.asp?id=181
I have an obsession with wooden jewelry. I have two cuffs from here. One thin plain wood and the other thick with the resin on it. I love them! I have a really skinny wrist and you can order by size, so it works out well.
http://www.cerodesigns.com/