The Bowlingual Translator claims to decode up to 5,000 sample voiceprints so you can now undersatnd what your dog is feeling. I can save you the $50 by telling you that you're dog is hungry or it wants to go out. Seriously, if you need a device to tell you what your dog is thinking, you might need to examine your deductive skills.
This device claims no only to be able to recognize the many different barks of different dogs but also provides a data analysis mode, a body language mode, a medical reference mode and a training mode.
As fun as this gadget may seem, I recommend just watching the Dog Whisperer on TV for free (if you have cable or satellite).