My family website has literally thousands of photos and, to make life easier, I use Sebastien Windal’s mkthumb to automatically generate thumbnails. This works fine but doesn’t use the Exif orientation information in Jpegs (at least from my Nikon) to rotate thumbnails appropriately.
So I made a few minor changes, and voila! I also changed gdImageCopyResampled (better quality, slower) to gdImageCopyResized (lower quality, much faster). For thumbnails, the difference in quality is neither visible nor worth the extra processing time.
If anyone’s interested, I also have some ruby, php and perl scripts that, combined with simpleviewer, make a simple bulk photo web album.