Plotly Python Library
Plotly's Python graphing library makes interactive, publication-quality graphs online. Examples of how to make line plots, scatter plots, area charts, bar charts, error bars, box plots, histograms, heatmaps, subplots, multiple-axes, polar charts and bubble charts.
All Plotly charts have click, hover and zoom events exposed to add custom controls with Plotly's JavaScript postMessage API.
Plotly is a web-connected service by default, but can also work entirely offline within the IPython Notebook.