This is a similar idea to Bob's script suggestion but uses 3dZcutup instead of from3d to extract slices.
#!/bin/tcsh
# coronalslices
# extract coronal slices to separate NIFTI datasets
# usage:
# coronalslices dset
if ($1 != "") then
set DSET = $1
else
set DSET = anat+orig
endif
set OUTDSET = "tempdset_cor"
3dresample -orient RSA -prefix ${OUTDSET} -inset ${DSET}
set dims = `3dAttribute -all ${OUTDSET}+orig |grep DATASET_DIMENSIONS`
set nslices = $dims[5]
foreach a (`count -d 3 0 $nslices`)
3dZcutup -keep $a $a -prefix ${OUTDSET}_slice${a}.nii ${OUTDSET}+orig
end
echo "Put slices back together again with 3dZcat"