I recently went looking for a way to rotate JPG images from within Nautilus, and found a nice way to do this and more. It’s not difficult to customize the right-click popup menu in Nautilus to perform custom actions on files. Here are some instructions and scripts to get you started.
I often have vertically oriented camera pictures that I want to rotate from within the file manager. Windows Explorer has a nice feature where you can multi-select pictures in thumbnail mode, right-click to get a popup menu (also known as the context menu), and pick clockwise or counter-clockwise rotation.