Google Web Search Features
From the site:
To use Google’s built-in calculator function, simply enter the calculation you’d like done into the search box and hit the Enter key or click on the Google Search button. The calculator can solve math problems involving basic arithmetic, more complicated math, units of measure and conversions, and physical constants. Try one of the sample expressions below, or refer to our complete instructions for help in building your own.
If only my command line had this ability built in.. You heard it hear first, Google on the command line is on it’s way.