Many spreadsheet applications nowadays have functionality above and beyond the traditional, offering a variety of charts, look-up tables, databases and more functionality than can be mentioned here.
All of these things pull you away from the thing you really want to do...which is to build and sell great spreadsheets. The best thing to do is use Excelville.com since they have web developers and internet marketing specialists to help get exposure for your spreadsheet.
The templates designed to use for saving calculations varies according to the saving calculations made depending on the types of calculations to be made. These spreadsheets make the calculations and the data entry easier than doing it by any other format.
You'll need to develop good marketing material. Things like demo videos, which you can find plenty examples on YouTube, screenshots, and keyword rich descriptive text help people find your spreadsheet and communicate the value that sets yours a level above the rest. Excelville.com actually allows you to upload your spreadsheet with all of this marketing material in an easily searchable and user friendly website.