When it comes to deploying a HTTP webserver, you will most probably think about using Apache HTTPD. After all, this is the most used and versatile web server around there. It also comes under the very nice Apache software license. There are fortunately other server choices (remember that a monopoly is never fruitful, even if the software is opensourced).

If you were on crack and stupid forced to, you could deploy the second most-used web server: Microsoft IIS. But of course you are not dumb you'd rather deploy on a Unix-style box, so you may prefer using something else. An increasingly popular choice is LightHTTPD.

As the name suggests, it is (ways!) lighter than Apache HTTPD. It is especially efficient on static files and FastCGI applications. It is interesting to note that it can run this crap of PHP faster using FastCGI than Apache does with mod_php which is the most common way of deploying it. It also has many of the features that you want (rewriting, proxy-ing, authentification, caching, ...) and some others that are quite innovative (ex: FLV files seeking). It's been already in use by some of the most popular websites: Wikipedia, Youtube and Meebo to name a few.

If you have been striked by the grammar of Apache HTTPD configuration files (do you like mod_rewrite?), you will also enjoy the (arguably) better syntax of the LightHTTP configuration file. For an excellent introduction to LightHTTP, I suggest that you read this Oreilly ONLamp article.

Don't get me wrong: if you have stable servers running Apache HTTPD, it may not be worth making a migration. But if you start experimenting scalability issues, or if you are planning to deploy a new web server, then you might seriously think about using LighHTTPD for a change!