Straighten & Crop by Bert Hinz

This plugin is by Bert Hinz. As his web site seems to be down, I'm archiving it here. It says it's "free software" (looks like part of the GPL Licence) so I'm assuming this is OK. Description from the script:

# ==============================================================================
# StraightenCrop.py V1 - (c) Bert Hinz 2008
# ==============================================================================
#
# IMAGE ROTATION AND CROP FOR THE GIMP
#
# Straightens the image vertically or horizontically and crops with minimal loss
# of image area.
#
# ==============================================================================
#
# INSTRUCTIONS:
#
# Use the path tool of the GIMP to position two points on a line or edge of an
# object you want straighten vertically or horizontally:
#
# Press "B" to activate the path tool. Then put the points by single left-clicks
# without holding the mouse key while moving the mouse. Finally run
# /Image/Transform/Straighten & Crop.
# Press "Ctrl & Z" to undo the crop if required.
#
# Menu location on systems with German local settings:
# /Bild/Transformation/Straighten & Crop