Servlet that act as a reverse proxy.
The project is hosted in maven central. here you'll find a quick copy/paste for the dependency.
Based on ProxiServlet from Jason Edwards, available under the Apache Licence V2 http://edwardstx.net/wiki/Wiki.jsp?page=HttpProxyServlet
Patched to skip "Transfer-Encoding: chunked" headers, and avoid double slashes in proxied URL's. http://code.google.com/p/google-web-toolkit/issues/detail?id=3131#c40
See also http://raibledesigns.com/rd/entry/how_to_do_cross_domain