DatPlot

DatPlot lets you plot graphs using data sets in TXT, CSV, or similar formats. You can create line or scatter plots, label events at particular points, and easily swap the axes.

Zooming and panning is quite easy - you can restrict the zooming to just the X or Y axis. You can also save your plot, along with all the labels and zoom settings, to a DatPlot (*.dpm) file.