Borland: Silk & Gauntlet
Borland Software Quality Solutions - build high availability, accuracy and performance into business-critical software applications with automated, easy-to-use software quality assurance, management and control technologies.
http://www.borland.com/us/products/silk/

AdventNet QEngine
Load Testing and Functional Testing Tool For Web Applications and Web Services. Download Now. Supports HTTP/ HTTPs, SOAP Web Services Testing.
http://www.adventnet.com/products/qengine/index.html

StressTester
StressTester(tm) has been independently certified as being the easiest to use performance testing tool available.
http://www.stresstester.net/

Testing Master
Web site testing with website testing tool Testing Master. Website testing tool emulate real users activity and you can check how web site performs under stress loads.
http://www.siteloadtesting.com/

Testing Automation
Specialists in automated software testing, especially Mercury Interactive's and Omsphere's testing tools. Developers of the Decision Engine Simulator tool.
http://www.testingautomation.com/

ANTS
.NET tools for developers, including a code and memory profiler and a tool for detecting unhandled exceptions in your code.
http://www.red-gate.com/advanced_dotnet_testing_system.htm

Test Tool for IVR's
Voice Prover, a tool for IVR volume testing and IVR monitoring
http://www.havenbr.demon.co.uk

WET
WET is a opensource web automation testing tool which uses Watir as the library to drive web pages. WET drives an IE Browser directly and so the automated testing done using WET is equivalent to how a user would drive the web pages
http://wet.qantom.org/

Webcorder
AS400, iseries, software testing
http://www.crimsonsolutions.co.uk/

BugHuntress Testing Tools
Offers a testing tool for Palm applications which requires no additional hardware as well as unit test frameworks for the Brew and Symbian platforms. [Commercial]
http://www.bughuntress.com/modules.php?name=Pages&show_page=products.html