How to display sagittal/coronal views in ImageJ?

http://rsbweb.nih.gov/ij/docs/menus/image.html

Reslice...

Reconstructs one or more orthogonal slices through the image volume
represented by the current stack. Before using this command, create a
straight line or rectangular selection to specify were the
reconstructions will be done. A dialog box allows you the specify the
Z-Spacing (displacement between slices) of the source volume. Multiple
slices are reconstructed and saved as a stack if you create a
rectangular selection or set Slice Width greater than one.

Images are created by sampling each slice in the stack along the line.
Thus, the first pixel in each row of the output image is taken from
the start of the line and the last from the end. In the case where
Slice Width is greater than one, a stack is created by shifting the
line down and to the left to generate additional slices for the output
stack.

This plugin, and the ZProject plugin, were contributed by Patrick
Kelly and Harvey Karten of the University of California, San Diego.