Thanks for your comments. I think you have a couple of options for white matter tracts

Connectopedia is a fantastic tool from Denis Ducreux that uses the MRIcroGL engine for rendering. You can use it on its own or use the images with other tools. You can use the images within Connectopedia or with other tools (as I recall, with OSX you have to 'show package contents' to see the images). These are high quality maps from a single individual:
 http://www.connectopedia.org

Marco Catani and his team have created some nice probabilistic white matter maps based on a group of indiviuals.
http://www.natbrainlab.com