I've evaluated two excellent programs for load-balancing TCP connections to my LDAP servers. The first, balance I like very much because it delivers status information on the state of connections. Furthermore, an administrator can enable, disable or even add further backend servers at will without restarting the load balancer.
The second is called PEN. I like this because, contrary to balance, it will disable unreacheable backend servers for a specific period of time, whereas balance requires an external program to disable the target channels.
I'm not quite sure yet which of the two will win the race; I'm currently evaluating PEN in a long-term test and will report both good and bad findings at a later point in time.