Shell Scripts..Can one be written to load balance a network?

I was wondering if it would be efficient to write a Shell Script to act as a load balancing redundant safety feature. For example if Server A failed due to equipment failure, Server B and C would balance the load and give the Admin time to resolve the Server issue at his leisure, not ruining a weekend with the family.
If the company were running Windows Server 2003 would its Network Load Balancing (NLB) do the same thing making the Shell Script obsolete?