My apologies if I am telling you what you already know.

No recommendations, but there are quite a few thing that look as though they will work. The ones that are familiar to me are high performance http servers: Lighttpd (I like the config syntax), nginx (most popular choice, and probably highest performance) or even Cherokee (gui config, least active devs) should be able to do it.

I also think Pound should be able to do it too. There are a host of others that may do.

I don't see how it would work doing the load balancing at the web server level. At that point, the request is already at the web server (which may be the wrong server for the intended content).

And without a load balancer between the user and the web servers, how are you determining which web server is to be used to process the request in the first place?

Pound looks like it may fit the bill though. It was one I put on my short list to look at in more detail.

I did not make myself clear. I was suggesting that you use a fast web server as a proxy. Nginx is quite often used this way.

see:

[cherokee-project.com ]

It looks like we're going to go with Zen load balancer- pretty easy to setup and do basic configuration.

The documentation is a bit lacking on details for setting up granular rules. But Google came through and I managed to get it setup to do what I wanted it to do with URL-based rules.