A [Java reporting tool|http://www.jasperforge.org/jaspersoft/opensource/business_intelligence/jasperreports/]. 

JasperReports is a powerful report-generating tool that has the ability to deliver rich content onto the screen, to the printer or into PDF, HTML, XLS, CSV, and XML files. JasperReports is entirely written in Java and can be used in a variety of Java enabled applications, including J2EE or Web applications, to generate dynamic content.

Its main purpose is to help creating page oriented, ready to print documents in a simple and flexible manner.

[jasper samples]

[DynamicReports|http://dynamicreports.sourceforge.net/] - Open source Java API reporting library based on JasperReports

Also, a [Sinclair Spectrum emulator|http://www.spectrum.lovely.net/], 
a [Java class disassembler|http://www.angelfire.com/tx4/cus/jasper/],
and [Tomcat's JSP compiler portion|http://jakarta.apache.org/tomcat/tomcat-4.0-doc/jasper/docs/api/index.html].