Microsoft Excel. Manipulating tens or hundreds of thousands of rows, including cross-referencing across tables, is just so satisfying and much faster than doing it with a DB or code. Alternative spreadsheet software do some things better, but they don't come close as a complete package, I don't regret paying for it myself for the first time in my life. It such a life saver in a pinch.
Obligatory Spolsky intro to Excel: https://www.youtube.com/watch?v=0nbkaYsR94c