Google Web Search Features: "Calculator
To use Google's built-in calculator function, simply enter the expression you'd like evaluated in the search box and hit the Enter key or click the Google Search button. The calculator can evaluate mathematical expressions involving basic arithmetic (5+2*2 or 2^20), more complicated math (sine(30 degrees) or e^(i pi)+1), units of measure and conversions (100 miles in kilometers or 160 pounds * 4000 feet in Calories), and physical constants (1 a.u./c or G*mass of earth/radius of earth^2). You can also experiment with other numbering systems, including hexadecimal and binary."
I've posted previously about Google's insidious invasion of the PC. No-one else does the "computer as network" as Google does.
Having an always at hand super convenient scientific calculator is actually kind of useful. Quicker than having to bring up the windows calculator. They don't say how to find documentation (ex: do they do financial calculations, such as interest payments)?
The Web features page is worth bookmarking and returning too.