You may want to look at using something like the Tiles mechanism that is part of the Struts framework.
(There are other alternatives but, as I'm not familiar with them, I'll leave the description these to somebody else)
Whether is based purely on JSP files or a combination of servlets and JSPs, you'll gain a great deal of re-use from adding Tiles support.
There are lots of tutorials on the web, a notable example being a sample chapter from a Ted Husted (Very active figure on this subject) book. http://www.manning-source.com/books/husted/husted_ch11.pdf
Give it try - I'm sure you'll like it.