For JBoss AS 5.1 the root web app is located server/xxx/deploy/ROOT.war - you could locate everything there.
You could also create the directory server/xxx/deploy/static.war and place everything in there, and then access it via a url like http://hostname:8080/static/some.css
Thanks, PeterJ. Is it possible to use relative paths to access the global resources in either root or static if the apps are located on the same server?
No. Relative paths always are restricted to the web application's directory, otherwise you will have a huge security hole.