Does a module for real-time data plotting exist?
Google Chart Tools


  Display live data on your site using Google Chart Tools Google Chart
  Tools module provides a simple API to Build custom interactive SVG
  charts.
  
  Views integration
  
  The Google Chart Tools Views module is based on the Views built in
  aggregation function. For basic instructions of using the Views
  integration module check the README.txt file


or

Quant provides an engine for producing quantitative, time-based analytics for virtually any Drupal component. Quant takes raw data about normal Drupal actions, such as node creation, and plots the activity over time, with the selected time being configurable. See the screenshot provided for a better understanding.


  Quant API (easily provide your own charts)
  
  The real power of Quant lies in it's ability to generate these charts
  with very little provided information. Quant offers a simple, yet
  flexible API to allow developers to include quant charts with their
  modules.