Load Testing

[Drakkon]

Are there any great apps for checking the load of simulated multiple users on a web server?
I like http://www.webperformanceinc.com/ but they charge a "virtual user" license thats outrageous. I'd like to find something priced under $1000.

 

[quikah]

Opensta is OK, it is free, http://www.opensta.org/ can be a little tricky to use though.