Any free WPF themes?
I bought a theme from www.xamltemplates.net. The themes ship with source code so you can tweak them. They also offer a free theme (source code included).
Not purely themes, but MahApps.Metro provides Windows 8 Look and feel with a few variants like dark and light base themes with green,blue etc for text and others. Its pretty cool and can be used out of the box.
The only one that I have found (for sale) is reuxables. A little pricey, if you ask me, but you do get 9 themes/61 variations.
UPDATE 1:
A WPF Contrib project ... which does have 1 theme that they never released.
UPDATE 2:
Rudi Grobler (above) just created CodePlex community for this ... starting with converted themes he mentions above. See his blog post for more info. Way to go Rudi!
UPDATE 3:
As another answer below has mentioned, since this question and my answer were written, the WPF Toolkit has incorporated some free themes, in particular, the themes from the Silverlight Toolkit. Rudi's project goes a little further and adds several more ... but depending on your situation, the WPF Toolkit might be all you need (and you might be installing it already).