Does your desk real estate also include room for a calculator in this modern age, or do you just rely on your computer for computations? If the designer behind the OS Calculator ever brings this concept into reality, you could have both. OS Calculators are the same simple programs you know and love, faithfully recreated — even down to the drop-down menus on the Windows version. Those, uh, probably don't work, though.
There's also one for Mac fans, as seen down below.