software for visual data editing?

Say you generate chart in excel, but you could edit data directly by moving datapoint or group of datapoints in your chart with your mouse? Maybe you want to draw freehand over the graph and generate new datapoints and thus updating original data.

I found a few apps that have this functionality as part of some huge bloated package, but none of them really work as they should. What i need is to import, edit and export ascii file.

It seems 100% of programmers have no idea what the fuck their users actually need.