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.
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.
You could make money doing something you love (or like [or maybe not so much but just really good at]). It's great to see a spreadsheet come together, and usually a lot better than what you originally envisioned. Especially when the dang thing works.
You can also create a calendar with a spreadsheet application and keep it within your budgeting workbook. You can list dates bills are due and you can also use the calendar in accordance with your budget to plan for special items or vacations. Having everything in one place will make it easier to manage your finances and plan for the future.
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