A chart of the square root of the absolute standardized residuals by fitted values. Also known as a Spread-Location or S-L plot.
For example:
The following example shows the results from this plot from a Regression - Poisson Regression output.
Acknowledgements
Uses the plot.lm or plot.glm functions from the stats R package.
References
Belsley, D. A., Kuh, E. and Welsch, R. E. (1980). Regression Diagnostics. New York, NY: Wiley.