What is a common web architecture for java apps?

Question

Im currently developing a java web application, and im researching how i should combine different types of technology in order to get the most use of a single webserver.

My plan so far is to have the following architecture setup

Internet ->
Varnish (reverse proxy) ->
Apache2 (mod_pagespeed, mod_jk) -> 
Ehcache-web (caching html page fragments,spring-cache) ->
Tomcat (java appsrv) ->
Ehcache (cache layer) -> 
MySQL (persistance layer)

Is there any problems with this design? What about scaling and clustering when it comes to that? Is there any other (better) solutions?

Thanks!