You can find it for free at http://nginx.org/ I find nginx is simpler to setup than pound (it's not hard but I found it unintuitive and annoying), it seemed to make some basic setups overly complicated with the config file syntax.
nginx on the other hand is perfectly suited in everyway, it is even simpler to setup and seems to be the most stable and most efficient any load balancer. I would go as far as to say that a good nginx setup is more relia........