Here is a brief howto to get virtual hosts working. I have looked all over this forum and I could not find a good HOWTO so I am going to post my configs. This worked for me on Ubuntu 7.10 with JBoss AS 4.2.1 GA. I have an internal DNS record for www.test1.com and www.test2.com that resolves to a single IP.

Apache mod proxy + JBoss AS virtual host example

/etc/apache2/httpd.conf

ProxyRequests Off

<Proxy *>
 Order deny,allow
 Allow from all
</Proxy>

NameVirtualHost 192.168.1.93:80

<VirtualHost 192.168.1.93:80>
 ServerName www.test1.com
 ProxyPass / http://www.test.com:8380/
</VirtualHost>

<VirtualHost 192.168.1.93:80>
 ServerName www.test2.com
 ProxyPass / http://www.test2.com:8380/
</VirtualHost>

jboss/server/default/deploy/test1.war/WEB-INF/jboss-web.xml

<?xml version="1.0"?>
<jboss-web>
 <context-root>/</context-root>
 <virtual-host>www.test1.com</virtual-host>
</jboss-web>

jboss/server/default/deploy/test2.war/WEB-INF/jboss-web.xml

<?xml version="1.0"?>
<jboss-web>
 <context-root>/</context-root>
 <virtual-host>www.test2.com</virtual-host>
</jboss-web>

jboss/server/default/deploy/jboss-web.deployer/server.xml

<Server>

 <!--APR library loader. Documentation at /docs/apr.html -->
 <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
 <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html -->
 <Listener className="org.apache.catalina.core.JasperListener" />

 <!-- Use a custom version of StandardService that allows the
 connectors to be started independent of the normal lifecycle
 start to allow web apps to be deployed before starting the
 connectors.
 -->
 <Service name="jboss.web">

 <!-- A "Connector" represents an endpoint by which requests are received
 and responses are returned. Documentation at :
 Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
 Java AJP Connector: /docs/config/ajp.html
 APR (HTTP/AJP) Connector: /docs/apr.html
 Define a non-SSL HTTP/1.1 Connector on port 8080
 -->
 <Connector port="8380" address="${jboss.bind.address}"
 maxThreads="250" maxHttpHeaderSize="8192"
 emptySessionPath="true" protocol="HTTP/1.1"
 enableLookups="false" redirectPort="8443" acceptCount="100"
 connectionTimeout="20000" disableUploadTimeout="true" />

 <!-- Define a SSL HTTP/1.1 Connector on port 8443
 This connector uses the JSSE configuration, when using APR, the
 connector should be using the OpenSSL style configuration
 described in the APR documentation -->
 <!--
 <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
 maxThreads="150" scheme="https" secure="true"
 clientAuth="false" sslProtocol="TLS" />
 -->

 <!-- Define an AJP 1.3 Connector on port 8009 -->
 <Connector port="8009" address="${jboss.bind.address}" protocol="AJP/1.3"
 emptySessionPath="true" enableLookups="false" redirectPort="8443" />

 <Engine name="jboss.web" defaultHost="localhost">

 <!-- The JAAS based authentication and authorization realm implementation
 that is compatible with the jboss 3.2.x realm implementation.
 - certificatePrincipal : the class name of the
 org.jboss.security.auth.certs.CertificatePrincipal impl
 used for mapping X509[] cert chains to a Princpal.
 - allRolesMode : how to handle an auth-constraint with a role-name=*,
 one of strict, authOnly, strictAuthOnly
 + strict = Use the strict servlet spec interpretation which requires
 that the user have one of the web-app/security-role/role-name
 + authOnly = Allow any authenticated user
 + strictAuthOnly = Allow any authenticated user only if there are no
 web-app/security-roles
 -->
 <Realm className="org.jboss.web.tomcat.security.JBossSecurityMgrRealm"
 certificatePrincipal="org.jboss.security.auth.certs.SubjectDNMapping"
 allRolesMode="authOnly"
 />
 <!-- A subclass of JBossSecurityMgrRealm that uses the authentication
 behavior of JBossSecurityMgrRealm, but overrides the authorization
 checks to use JACC permissions with the current java.security.Policy
 to determine authorized access.
 - allRolesMode : how to handle an auth-constraint with a role-name=*,
 one of strict, authOnly, strictAuthOnly
 + strict = Use the strict servlet spec interpretation which requires
 that the user have one of the web-app/security-role/role-name
 + authOnly = Allow any authenticated user
 + strictAuthOnly = Allow any authenticated user only if there are no
 web-app/security-roles
 <Realm className="org.jboss.web.tomcat.security.JaccAuthorizationRealm"
 certificatePrincipal="org.jboss.security.auth.certs.SubjectDNMapping"
 allRolesMode="authOnly"
 />
 -->

 <Host name="localhost"
 autoDeploy="false" deployOnStartup="false" deployXML="false"
 configClass="org.jboss.web.tomcat.security.config.JBossContextConfig"
 >

 <!-- Uncomment to enable request dumper. This Valve "logs interesting
 contents from the specified Request (before processing) and the
 corresponding Response (after processing). It is especially useful
 in debugging problems related to headers and cookies."
 -->
 <!--
 <Valve className="org.apache.catalina.valves.RequestDumperValve" />
 -->

 <!-- Access logger -->
 <!--
 <Valve className="org.apache.catalina.valves.AccessLogValve"
 prefix="localhost_access_log." suffix=".log"
 pattern="common" directory="${jboss.server.home.dir}/log"
 resolveHosts="false" />
 -->

 <!-- Uncomment to enable single sign-on across web apps
 deployed to this host. Does not provide SSO across a cluster.

 If this valve is used, do not use the JBoss ClusteredSingleSignOn
 valve shown below.

 A new configuration attribute is available beginning with
 release 4.0.4:

 cookieDomain configures the domain to which the SSO cookie
 will be scoped (i.e. the set of hosts to
 which the cookie will be presented). By default
 the cookie is scoped to "/", meaning the host
 that presented it. Set cookieDomain to a
 wider domain (e.g. "xyz.com") to allow an SSO
 to span more than one hostname.
 -->
 <!--
 <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
 -->

 <!-- Uncomment to enable single sign-on across web apps
 deployed to this host AND to all other hosts in the cluster.

 If this valve is used, do not use the standard Tomcat SingleSignOn
 valve shown above.

 Valve uses a JBossCache instance to support SSO credential
 caching and replication across the cluster. The JBossCache
 instance must be configured separately. By default, the valve
 shares a JBossCache with the service that supports HttpSession
 replication. See the "jboss-web-cluster-service.xml" file in the
 server/all/deploy directory for cache configuration details.

 Besides the attributes supported by the standard Tomcat
 SingleSignOn valve (see the Tomcat docs), this version also
 supports the following attributes:

 cookieDomain see above

 treeCacheName JMX ObjectName of the JBossCache MBean used to
 support credential caching and replication across
 the cluster. If not set, the default value is
 "jboss.cache:service=TomcatClusteringCache", the
 standard ObjectName of the JBossCache MBean used
 to support session replication.
 -->
 <!--
 <Valve className="org.jboss.web.tomcat.service.sso.ClusteredSingleSignOn" />
 -->

 <!-- Check for unclosed connections and transaction terminated checks
 in servlets/jsps.

 Important: The dependency on the CachedConnectionManager
 in META-INF/jboss-service.xml must be uncommented, too
 -->
 <Valve className="org.jboss.web.tomcat.service.jca.CachedConnectionValve"
 cachedConnectionManagerObjectName="jboss.jca:service=CachedConnectionManager"
 transactionManagerObjectName="jboss:service=TransactionManager" />

 </Host>
 <Host name="test1" autoDeploy="false"
 deployOnStartup="false" deployXML="false">
 <Alias>www.test1.com</Alias>
 <Valve className="org.apache.catalina.valves.AccessLogValve"
 prefix="test1" suffix=".log" pattern="common"
 directory="${jboss.server.home.dir}/log"/>


 <DefaultContext cookies="true" crossContext="true" override="true"/>
 </Host>
 <Host name="test2" autoDeploy="false"
 deployOnStartup="false" deployXML="false">
 <Alias>www.test2.com</Alias>
 <Valve className="org.apache.catalina.valves.AccessLogValve"
 prefix="test2" suffix=".log" pattern="common"
 directory="${jboss.server.home.dir}/log"/>


 <DefaultContext cookies="true" crossContext="true" override="true"/>
 </Host>
 </Engine>

 </Service>

</Server>

This is a way that worked for me. If anyone, especially the developers see a flaw in my method please let me know. Or if anyone has a better way I would love to see it. This is the only way I could get it working.