Until now, I used a combination of Preview (to modify the EXIF orientation value) and PhotoToolCM (to do lossless JPG rotations) to achieve images that look correct both in Preview and in non-EXIF/web apps. Well, I finally found a program that both rotates the image and the thumbnail consistently! Enter the freeware Cheese by Stuffware.co.uk. This is a bare-bones program that has two basic purposes: rotate pictures properly, and allow you to add comments easily (it can also create web pages from your images).
Once you've rotated your pictures, here's a fast way to get your thumbnail icons to show correctly (i.e. refresh):
- Create a new folder (keep the untitled name)
- Move the affected images into the folder
- Using Column View, move the images back into the original folder.
- Delete the empty untitled folder.

