I use it to do super quick data analysis sometimes, and also I made a few spreadsheets to help my wife to manage our personal finance.
If your excel files have anything for forward planning and you want to share those files, I'd be interested.
Unfortunately there was no planning involved, one spreadsheet was just for her to put stuff she bought and the spreadsheet would calculate how much she spent in the month/week. Another one was for her to calculate how much the Saturday children center she is running would earn per month.
Since you made a webapp for personal finances, let me mention you the one a friend made: https://spendbook.net/main it doesn't do planning but I think he'll still be happy to get some feedback.