Just read about the <a href="http://www.apsis.ch/pound/">Pound Loadbalancer</a> for web traffic; although I've not implemented it, it looks slick. 

<p>
What do you guys use for load balancing apps (not just web)? </p><hr /><tt>We use a hardware load balancer.  Honestly it's the only experience I have with one.  Like most commercial products, the docs suck, but after pouring over them for a long time, it is a flexible piece of equipment.

It's a Foundry Network Serveriron switch/lb.

 - nathan</tt>