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.
At present, some of the most requested types of spreadsheet packages in the market are: 'Spreadsheets for Small Businesses' and a subset of that: 'Spreadsheets for Actors'.
Size limitation : When a spreadsheet is first constructed and tested, the size tends to be small. However, as the spreadsheet grows with more and more data, it start slowing down, until it reaches that point where your feet go to sleep while you waiting for the re-calculation to finish.
Once you design the type of budgeting spreadsheets you want to use, it will be easy to copy it for subsequent months or years. You can also use just one sheet and create tabs for each month.
examples of spreadsheet packages
spreadsheet templates for tracking