I'm working on an interesting infinite canvas calculator called https://minusplus.app/. This is an infinite canvas, where you click anywhere and type numbers, Press space or enter, and it will automatically calculate. You can tag #, add comments, and I have added some great keyboard shortcuts, which make it efficient to calculate.

I am an SAP Finance consultant, and I have to do a lot of calculations daily. And after using this, I can't go back to any other normal calculator. :-D