Below you can find a table listing Zend Framework Components and their dependencies to other Zend Framework Components. This can help you if you need to have only single components instead of the complete Zend Framework.
A dependency of type "hard" indicates that the components or classes cannot function properly if the respective dependent component is not available, while a dependency of type "soft" indicates that the component may need the dependent component in special situations or with special adapters. At last a dependency of type "fix" indicated that these components or classes are in any case used by subcomponents, and a dependency of type "sub" indicates that these components can be used by subcomponents in special situations or with special adapters.
Even if it's possible to separate single components for usage from the complete Zend Framework you should keep in mind that this can lead to problems when files are missed or components are used dynamically.
Table 174. Zend Framework Components and their dependency to other Zend Framework Components