A DTI analysis tutorial by Charlotte Rae is available here http://imaging.mrc-cbu.cam.ac.uk/imaging/DTItutorial
Older information
See SiemensDiffusionImages for an explanation of the images that the Siemens Trio writes out from a diffusion run.
Here are some notes on getting going with the fdt package for diffusion analysis in FSL: DiffusionFdtNotes
We had in informal meeting to share experience between the WBIC, FSL, and CSL: DiffusionMeeting10May2007