Panther client actually has Apache built in for personal web serving. It won't give you the robust reporting and features as you would have out of the box in server, but it's ample if you just want to simply push out some web content.
You can be creative and compile the open source tools from Server, as we discussed. Server will add things like WebDAV, SSL, WebMail service (in conjunction with mail), creation of multiple sites (including non standard ports to serve them from), default index pages, default directories for each site, admin email, IP address assignment per site to serve from, Performance Caching, CGI execution, Realms, Certificate authority and aliasing all from the GUI.
Of course, that's just what you can do per site, for the entire server, you have many options as far as MIME types to include, proxy servers to use and Apache modules as well.
That's not to say you couldn't get a lot of this functionality back through open source, I'm sure you could, but there is something to be said about the elegant style in which Apple provides all of this, plus remote management and reporting tools to you, right out of the box.
