This is a fantastic program, for free!
The one thing I wish it could do, so far, that it doesn't (unless I missed how to do it) is some sort of integration with iPhoto. The problem is, if one import one's images into iPhoto, (as opposed to just linking to them, an option in the iPhoto prefs) then all your photos are hidden away from the Finder inside the iPhoto library. In other words, you can't navigate to the iPhoto image via ImageEnlarger's source/browse buttons.
I tried changing the External Editor in the iPhoto prefs from PhotoShop or Graphic Converter (or whatever one uses) to ImageEnlarger, and although iPhoto does then switch to ImageEnlarger, it doesn't open the image one selected for External Editing in iPhoto.
If there's a way to do this that I've missed, I'd sure like to know, otherwise, I wish that this great little program was iPhoto savy.