NIfTI image data format
It is designed to contain enough information to supercede previous variants of the abused old FormatAnalyze. In particular it contains fields that allow the storage of transformation matrices to encode results of realignment, coregistration and normalization.
The current version (July 2006) is NIfTI-1. There is a new version in development, NIfTI-2.
See http://nifti.nimh.nih.gov/nifti-1 for documentation.
There is also a NIfTI FAQ - http://nifti.nimh.nih.gov/nifti-1/documentation/faq