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 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.
A popular category of ready-made spreadsheets mentioned earlier, is 'Spreadsheets for Actors'. 'Spreadsheets for Actors' includes sets of programmed spreadsheets that are especially designed for professionals in the entertainment industry, from Actors to Producers. The spreadsheets under 'Spreadsheets for Actors' range from facilitating the managing of budgets to keeping track of income emerging from many sources.
One user at a time : In the instance where there are a number of people required to work on a spreadsheet, they can only access it when no-one else is working on it.
types of spreadsheet
what is a spreadsheet used for
blank spreadsheet templates