I don't know if there's anything quite as nice as Django for Java, but Spring has a light-weight web framework built on J2EE
http://www.springframework.org/about
A flexible MVC web application
framework, built on core Spring
functionality. This framework is
highly configurable via strategy
interfaces, and accommodates multiple
view technologies like JSP, Velocity,
Tiles, iText, and POI. Note that a
Spring middle tier can easily be
combined with a web tier based on any
other web MVC framework, like Struts,
WebWork, or Tapestry.
