File Cabinet Pro is the file manager for the OS X menu bar. You can open, move, rename, tag, trash, copy and paste files, all from the menu bar.
File Cabinet Pro also comes with a built in Image Editor (you can turn this feature off in Settings and open your images in another application if you want).
In this little video, I show you how you can crop an image with File Cabinet Pro. Simply make a selection with the crop tool and then double click inside the selection box.