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.
However, companies can nowadays achieve these goals with less effort and in a cheaper way by using properly designed spreadsheets. The right spreadsheet solutions allow companies of all shapes and sizes to achieve and maintain a prominent position on the market, optimizing and accelerating a wide range of specific business processes and tasks.
Protection of formulae : How often have you forgotten to protect the cell contains the formula that took you hours to test and perfect. It takes one instance of honest human error, and that formula is gone.
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.
examples of spreadsheet packages
types of spreadsheet
what is spreadsheet in excel