I've been complaining about iPhoto's Crop command for years (generally to Apple). Crop worked, then it got erratic, then I complained, and then Apple disimproved it, removing the flaky feature (Keyboard shortcut? Something like that). This removed the bug from their dashboard at a cost in functionality and convenience

In iPhoto 7 (iLife 08), cropping is much improved. Hit the 'c' key to start a crop. Since grabbing the handles is problematic with top and bottom strips that flash over the photo at the edges of the screen, iPhoto helpfully (in full-screen Edit mode) shrinks the whole photo to not touch the edges. It looks strange, but helps a lot. When done, hit Enter to perform the crop.

There are still several rough edges, though:

  1. Sometimes the un-cropped image appears. This is confusing!
  2. iPhoto 6 always set a consistent proportional default crop area when selecting a new image. I liked this, as it offered a standard (relative) resolution when cropping photos, and I used that suggested size to sizes some photos the same. This is minor, but I miss it.
  3. The crop constraint (I normally use "4 x 3 (Book)", which can be inverted with the Option key) sometimes gets unset; it should stay the way I set it (ideally, even across launches of iPhoto). Additionally, when the Crop checkbox clears itself, the proportion flips back to "3072 x 2304 (Original)" on images from my Canon PowerShot SD800IS.
  4. The default crop constraint (original) for some reason cannot be inverted with Option, so I have to switch to "4 x 3 (Book)" when I want to crop "crossways".