We can use it as diary and record all important activities, to do list etc. These days spreadsheet is one of the most common program which you can find almost everywhere, be it personal computer, PDA, and the like. Such an easy availability and supports give you sheer freedom to view your data, no matter wherever you are.
To keep our financial, investment, tax, health, birthdays information and the like. We can use it for simple as well as specialized calculations. Like, comparing cost and returns of various loan, investment and insurance options available in the market.