Google's implemented a 34-button calculator as a part of its search engine functions. Now, if you're sans calculator or just feeling lazy, Googling simple arithmetic problems won't just yield you the answer, but the answer punched into a fully-functioning calculator.
While the calculator isn't fancy enough to replace Wolfram Alpha when doing higher-level mathematics, it's definitely a nifty tool to use. The calculator's also been implemented on Google's mobile search engine, where the calculator is as smooth and easy to use as an installed calculator app on a smartphone.
The calculator seems to be a part of Google's Knowledge Graph initiative, which the company just launched last month to make web searches for users much more in-depth and intuitive.