This Shadow&Highlight script does a decent job of lightening shadows and/or darken highlights in photographs. The UI gives you five control sliders. Two for control of the Shadow and Highlight amount (opacity), two for the tonal width of each contrast mask layer (using gamma), and one for the blur radius of the masks. Plus the option to flatten visible layers when done.
Every paper size has a different shape, and none probably match the shape of the images produced by your digital camera. This little utility will create a layer showing which parts of an image will fit on the paper when printed. A wide selection of print sizes are included. Using it will help you layout your image so that important pieces aren't cut off by the printer/lab.
This script-fu was developed under Gimp-2.0 and Gimp-2.4
A Gimp script-fu that gives a Midnight Sepia effect as described
1. Create a duplicate of the first Layer
2. Apply a Gaussian Blur on the top Layer
3. Use Hue/Saturation
Check the Colorize Option
4. Change the Blending Mode to Multiply
5. Flatten the Image
6. Duplicate the Layer
7. Change the Blending Mode to Screen
8. Flatten the Image
9. Duplicate the Layer
10. Change the Blending Mode to Screen
11. Adjust the Opacity to taste