Here's my take on how to watermark a ton of pictures (of different sizes and orientations) using the Actions and Image Processor features in Photoshop CS6.
It's my first tutorial so I'd appreciate your constructive criticisms! I felt like I was trying hard to sound professional during the whole tutorial. Nevertheless, I hope you learned something from this! Let me know if you have better ideas on how to watermark a bunch of pictures without doing it one by one.