These are open source alternatives to Jasperreports
BIRT (free BI suite) is an open source software project that provides the BIRT technology platform to create data visualizations and reports that can be embedded into rich client and web applications, especially those based on Java and Java EE. BIRT is a top-level software project within the Eclipse Foundation.
Pentaho Community provides everything an organisation might need to address not only its reporting needs, but also data mining for predictive analytics applications. The skill level required to make it all work should not be underestimated, but this is the case with most open source solutions. Bells and whistles (Dashboards etc) require a move to the Enterprise Edition of Pentaho.
ReportServer provides an extremely flexible open source reporting and dashboard environment. It supports Eclipse Birt, JasperReports and SAP Crystal Reports reporting engines in addition to its own ad-hoc oriented reporting tools. The user interface is web based and it supports a wide range of admin tools.
SpagoBI (free BI suite) is essentially a very large collection of open source software brought together to create a broad business intelligence capability. In fact it goes beyond the traditional notion of BI to embrace domains such as data mining and BPM.