ASP.NET Stress Testing
- HP (formerly Mercury) LoadRunner or Performance Center
- Visual Studio Application Center Test (Enterprise Editions only?)
- Microsoft Web Application Stress Tool (aka WAST, aka "Homer"; predecessor to Application Center Test)
- RadView WebLoad
After surveying a lot of open source and paid tools, I found the most success with Microsoft's Visual Studio 2008 Team Suite Test Edition (soon to be part of Visual Studio 2010 Ultimate). It has strong stress testing functionality. Microsoft's free application for stress-testing, WCAT is underpowered and buggy, but the full blown Test Edition goes up against products like LoadRunner but is easier to use, better-integrated with VS/ASP.NET and for much less money per virtual user.