SysAdminGear

Load balancing is a technique used by professionals that need to provide uptime, response time and reliability on their servers. Bank servers, Big site business are using it to protect their name.
It can be used is web applications like web, voip, cache, dns, mail, ftp etc.

Linux Virtual Server - LVS
Is open source Linux load sharing and balancing software that can be used to easily build a high-performance and highly available server for Linux using this software.

"Virtual server is a highly scalable and highly available server built on a
cluster of real servers. The architecture of server cluster is fully transparent
to end users, and the users interact with the cluster system as if it were only
a single high-performance virtual server. "