Polipo - A small and fast caching web proxy (a web cache, an HTTP proxy, a proxy server).
Privoxy - Privoxy helps users to protect their privacy.
Artica Proxy - Artica Proxy is an appliance that claim to manage Squid-cache proxy with all features that Squid...
Proxomitron - Information and resources for the Proxomitron user.
CacheGuard-OS - CacheGuard is an enterprise grade Web Gateway solution offering Web Security & Optimization in the same box. Price starting at $99 per Year!
ExaProxy - ExaProxy is a a high-performance non-caching proxy.