The OS X 10.4 version of Preview (/Applications) includes a handy slideshow tool (View: Slideshow, or just Shift-Command-F) which makes it a breeze to quickly review a number of images. An onscreen controller lets you pause the slideshow, view all the images as an index sheet, toggle between Fit To Screen and Actual Size mode for an image, add and image to iPhoto, and exit slideshow mode.
If you prefer using the keyboard instead of the mouse, you can use the arrow keys to move between each image in your slideshow. That part may have been obvious. What may not have been so obvious, though, is that Preview offers a few other timesaving keyboard shortcuts:
- Press A to view an image at its actual size.
- Press F to zoom an image to fill the screen.
- Press I to view the index page. On the index page, you can use the arrow keys to select an image and then press Return to view the selected image.
Here’s what the index page looks like in Preview’s slideshow mode:

Unfortunately, there doesn’t seem to be a shortcut for the Add To iPhoto controller button, so you’ll have to pull the mouse out for that action (someone, please, correct me if I’m wrong!).