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.
When your spreadsheet start to hit its limits, what options are open to you? Perhaps the best option is to consider the conversion of your spreadsheet to a database solution. Relational databases became viable not too long after the spreadsheet was well-entrenched as the affordable and quick means of gathering data and performing calculations.
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.
The mentioned package includes valuable programmed spreadsheets such as the "Income and Residual Tracker" - provides professionals in the entertainment branch with detailed information regular and residual income; "The Biorhythm Plotter" - helps users in planning various events and actions based on Primary and Secondary Biorhythms (the spreadsheet solution allows users to choose the right timing for their actions according to personal intellectual, psychological and physiological factors); "Basic Actor Package" - designed to facilitate the process of calculating expenses.