Not the answer you are looking for, Matt, but I don't use one. As a rule, I dislike loading down my browsers with ad-in software of any kind: the more you have, the slower and less reliable the browser becomes. (This goes for any browser.) So when the built-in EXIF isn't detailed enough for me, I just rightclick, save, and open it with PMView or, if I want some really heavy-duty EXIF info, PhotoMe.

But you could try visiting opera.com and looking for an Opera widget (yes, that's what they call them, "widgets"). If there is one, and it's any good, it will be a genuine first .... the first widget I've ever heard of that does something useful!