rmtoo - rmtoo is a free and open source requirements management tool.

ReqView - Simple and powerful requirements management tool enabling easy requirements gathering, traceability tracking and offline collaboration.

Rational RequisitePro - The list below identifies the supported releases of IBM Rational RequisitePro from which you can select system requirements in different levels and organization of detail.

Jama Connect - The Leader in Requirements Management Solutions

Doorstop - Requirements management using version control.

Jama - Jama combines requirement management software with enterprise collaboration capabilities to solve product delivery problems.