HAproxy is a high-performance and highly-robust TCP/HTTP load balancer which 
provides cookie-based persistence, automatic failover, header insertion, 
deletion, modification on the fly, advanced logging contents to help trouble- 
shooting buggy applications and/or networks, and a few other features. It uses 
its own state machine to achieve up to ten thousands hits per second on modern 
hardware, even with thousands simultaneous connections. It currently lacks SSL 
and keep-alive, both of which are planned.

WWW: http://w.ods.org/tools/haproxy/