Java Content Repository API (JSR 170) 
This looks like an interesting technology to use for building content management systems within portals. Using these tools, you can
easily create
tree structured content management systems (think XML & DOM), that give a lot of extra functionality, such as searching, indexing, etc, for free.
Check it out, here is a tutorial at IBM DeveloperWorks that talks about the Apache implementation of the spec:
http://www-128.ibm.com/developerworks/java/library/j-jcr/index.html