You can build a reputation as an expert spreadsheet developer. This certainly doesn't hurt the resume. Using Excelville.com to sell spreadsheets allows you to set up a profile with your work, biography, and other info that certainly makes for good conversation material during interviews.
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.
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.
So you've got what it takes to develop spreadsheets that others would find useful. Now you're thinking about selling your spreadsheets to both help people and generate some additional income using your MS Excel or other spreadsheet development skills. Well, as you know, there are pros and cons to everything you do. Read on to find out what some of them are:
examples of spreadsheet packages
spreadsheet templates for small business