Open XML Java Library - God is in the details

Open XML Java Library
http://blogs.msdn.com/brian_jones/archive/2007/06/01/open-xml-java-library.aspx

http://www.openxml4j.org/
OpenXML4J is a Java library dedicated to the creation and manipulation of Office Open XML (ECMA-376) and OPC based documents (for example Office 2007 Word, Excel and PowerPoint documents). OpenXML4J provides you a way to create and manipulate Open XML documents for a bunch of scenarios without using any office suite.

http://www.codeplex.com/openxmljavademo
Project Description
Excel is the most commonly used financial tool in the market today. The new OpenXML standards allows Java programs to consume Excel spreadsheets directly and to create Excel spreadsheets on the fly. In this demo, a financial java web-application that monitors a portfolio in the stock market will generate, on demand, runtime Excel reports as well as keep the data in an internally kept Excel spreadsheets.