Proxyma is a multiple reverse-proxy library/webapplication with a cache subsystem and url-rewriting capabilities. The new core is based upon a flexible plugins subsystem easy to extend and customize. Recently this project was promoted to release 1.0.
jRevProxy is a lightweight reverse proxy server fully written in Java. jRevProxy accepts HTTP and HTTPS requests and translates these into new requests based on a set of rules. HTTPS with client side authentication (X509 certificates) is supported.
Oroena is a fully Java 2 Enterprise Edition powered Open Source Reverse Proxy engine. It provides unique session, security or server access management for a multi-server architectured portal.