Velocity is a view technology comparable to JSP) that Apache Portals officially supports. Many portlet developers feel Velocity is an excellent alternative to JSP for web application development.
Portals uses Log4j for a logging framework. No more commenting System.out.println()'s in your code!
Maven is a Java project management and project comprehension tool. Maven is based on the concept of a project object model (POM) in that all the artifacts produced by Maven are a result of consulting a well defined model for your project.
Maven article - Maven ties together tools for better code management. by Jeff Linwood, published in JavaWorld on October 11, 2002.
Velocity Introduction - Start up the Velocity Template Engine. by Geir Magnusson, Jr., published in JavaWorld on December 28, 2001.
The web application framework comparison project WAFER takes a look at the many web application frameworks available and makes a comparison.