I know two differnt ways. The first is the quick-and-dirty, the second the slow but correct version.
1) Create singleton classes are use the static lookup to find the information container. This works fine as long as all the web application are running in the same JVM but this is not ensured therefore for a production application hands-off.
2) Use a persistent data store to save the information and share them. This can be a DB, properties file etc.
Have fun - Andy
You could also consider using serialized Java objects stored in a JNDI directory.