A few days ago, I came across an interesting open-source GUI testing application called Sikuli. This tool promises to automate just about any procedure involving graphical elements displayed on the screen, using a vision engine to intelligently match regions of your GUI display to widgets where you might click, drag, or type things. Sikuli is distributed under the permissive MIT License.
We have run several different load tests for the Acushnet Golf company, primarily to evaluate the performance of their customized order management software. We were able to simulate a load of hundreds of users via Grinder, along with custom tools we developed such as Grinder Webtest.
This custom module for the Grinder load testing framework allows execution of Visual Studio "webtest" files. It supports parameterization, capturing of variables in HTTP responses, and response validation using regular expressions. Test scripts may be logically grouped into test sets, allowing them to share variables and captured values. Test sets can be run sequentially, randomly, in a specific thread, or according to a percentage-based weighting.