CurvedLines is a plugin for flot, which displays lines in a smooth curved way. This is achieved by adding additional points in between the "real" data points.
The plugin is based on nergal.dev's work and gives you an option to display curved lines. I further extended the code with a 2nd mode, which forces the lines to have their minima/maxima on the original data points.
Feel free to add additional features and correct errors.