It's important to have your copyright information included with every photo that goes out into the wild. Fortunately applications such as Aperture and Lightroom enable you to add copyright information during upload, making it easier to develop this healthy habit. But what can you do if you don't use those applications and sometimes forget to append your files? You can have your camera do it for you.
IPTC data readout from Adobe Bridge 2. The text in the "Creator" field was added by my Canon Rebel XTi during capture.
That's right, Canon DSLR owners can apply up to 30 characters of text to the metadata of every picture they take. This information appears in the "Creator" field when read in Bridge, in the "Author" field in Photoshop, and the "Owner Name" field in Preview. So even though it shows up in different IPTC fields in different applications, it does show up. I even added an image to iPhoto, then exported it out, and my copyright persisted through the export process.
Canon EOS Utility 2
Start by making sure you have the latest version of EOS Utility 2. Launch it, then connect your Canon DSLR. Once the application recognizes your camera, click on "Camera Settings/Remote Shooting." If the application doesn't recognize your camera, disconnect it, change the communication setting to "PC" (in Canon's set up menu), then reconnect.
Now click on the Tools icon and enter up to 30 characters in the "Owner's Name" field. You can't use symbols, so you'll have to spell out "copyright." Click OK, and you're set to go. Now, every time you take a picture, the info you entered will appear in the metadata of the picture.
This information persisted through every test I could throw at it except for one: "Save for Web" in Photoshop, which strips out all metadata. My advice, don't ever use Save for Web for your images. But do set up your Canon camera to write your copyright information to every photo.
I'm guessing that Nikon and other DSLRs offer similar capabilities. If you use one of these cameras and know how to apply this technique, please post in the comments field.