A different kind of calculator
stuifzand.eu
stuifzand.eu
http://www.acqualia.com/soulver/
Granted, Soulver is only available for OS X, but the author could at least give some credit to Acquilia for the idea.
Soulver is a fantastic piece of software, btw. I use it almost daily.
Having said that, I'll definitely be sharing a link to your software to all my Linux-user friends. The document-as-a-calculator concept is a fantastic. There's tremendous demand for it as well.
I like the fact one of the features for this app. is: "Addition, subtraction, multiplication and division are all supported".
If this thing ever gets traction, it will be because of this new 'multiplication' feature. Nobody I know uses division, and every calculator out there has some form of addition built-in. Of course, emacs already has it - try `M-x multiply-the-left-number-with-the-right-number-and-return-the-result`.