Jonathan Hardwick - Product information about Microsoft's System Center Capacity Planner. - http://blogs.msdn.com/jonathanh
Capacitas - Performance and capacity planning consultancy and training services. Includes whitepapers. Head office located in London, UK. - http://www.capacitas.co.uk/
Transaction Design Inc. - Consultant and tools vendor with focus on system monitoring, capacity planning, and benchmarking. Tools work on HP/Compaq/Tandem NonStop Kernel, Stratus VOS, and UNIX. Site includes articles on management/performance topics for these OSs. - http://www.banbottlenecks.com/
PerfCap Corporation - PerfCap Corporation provides Performance Management and Capacity Planning Products and Services. - http://www.perfcap.com
PerfCap UK - Offers web-based cross-platform performance analysis and capacity planning tool. Also provides consulting services. - http://www.perfcap.co.uk
RRD TOOL - A useful open source tool for storage and retrieval of time series data. - http://ee-staff.ethz.ch/~oetiker/webtools/rrdtool/
Red Hill Networks' WebSpray - This tool allows you to stress test your web server through a LAN or modem connection. It will generate reports for errors and performance. - http://www.redhillnetworks.com/products/webspray.htm
Schema - Schema is a provider of telecom resource management (TRM) solutions that enable operators of wireless networks worldwide to optimize and manage their resources. - http://www.schema.com
CIMS Lab, Inc. - Software and services for resource accounting, capacity planning, and IT chargeback. - http://www.cimslab.com
Load Balancing Your Web Site - Practical Approaches for Distributing HTTP Traffic by Ralf S.Engelschall. - http://www.webtechniques.com/archives/1998/05/engelschall/
Performance Dynamics Company - Develops performance tools, evaluates performance-related products, designs system benchmarks, and troubleshoots performance problems. Contact information, events calendar, and links to software tools. - http://www.perfdynamics.com/