If you enter http://localhost:8080, the welcome page that is displayed is located at JBOSS_HOME/server/default/deploy/jbossweb-tomcat55.sar/ROOT.war/index.html. If you simply want to change the links on the home page, editing that file will do.
However, do not deploy applications there. Instead deploy your application in the normal way (within the "deploy" directory), and add the following to your line to your jboss-web.xml file:
Your application's default page will then be displayed for http://localhost:8080.
I hope this helps.