there are a lot of framing script
i mostly use one from Insanity Prevail posted here and on DA but there are several for all kind of frames, mat+frame, semitransparent frames, gradient frame..
About photos i suppose "white balance" " color temperature" and "contrast mask" may be a good start for the scipt
i will add also 3 plugin "greycstoration" for noise removing "unsharpmask2 " for accurate sharpening and "liquid resize" for...well resize image without resize the content
And a good image viewer and converter useful also for quick but good correction on the fly as Xnview or Irfanview,
(if to be corrected is just the global contrast, hue , luminosity,contrast or saturation to me make no much sense open gimp for that, i prefer do on the fly when browsing.
obviously if to be corrected is not the whole only selected details then is needed gimp)
PS
white balance and color temperature are in
http://www.registry.gimp.org
if you use windows you may found "greycstoration" and "unsharpmask2" in my resources gallery (
http://www.photocomix-resources.deviantart.com/gallery/ )
