Squid Proxy - Website Content Acceleration and Distribution. Thousands of web-sites around the Internet use Squid to drastically increase their content delivery. Squid can reduce your server load and improve delivery speeds to clients.
CCProxy - Want to share Internet connection? Get every computer online through a single Internet connection?
3proxy - 3proxy freeware proxy server for Windows and Unix. HTTP, SOCKS, FTP, POP3
Varnish - High-performance HTTP accelerator
FreeProxy - Feature summary from website:* Internet connection sharing with demand dialling
Privoxy - Privoxy helps users to protect their privacy.