OSCache solves two fundamental problems of all dynamic sites:

- Caching Dynamic Content - Dynamic content must often be executed in some form each request, but sometimes that content doesn't change every request. Caching the whole page does not help because parts of the page change every request. OSCache solves this problem by providing a means to cache sections of JSP pages.

- Error Tolerance - If one error occurs somewhere on your dynamic page, chances are the whole page will be returned as an error, even if 95% of the page executed correctly. OSCache solves this problem by allowing you to serve the cached content in the event of an error, and then reporting the error appropriately.

The website is here : http://www.opensymphony.com/oscache

For what it's worth, there is a new OSCache release featuring:
* clustering support
* better configurability
* and many smaller improvmenets and bug fixes

Get it at http://www.opensymphony.com/oscache.

Enjoy!