I have seen that higher end "gaming" motherboards have 2 or 4 ethernet ports. In a typical home environment how does one utilize the additional ports? Is it perhaps something like a "dedicated" port between the media server and the extender?
You can either use the separate ports as:
1.) On separate networks (PC as a Router statement above). The ports MUST be on separate network segments.
2.) Aggregate - Using 802.3ad LACP. Will create a 2+ Gig channel. The switch must support this as well. In Cisco-land this is known as Etherchannel, other vendors call it Link Aggregation.
3.) Failover/Redundancy - This is vendor proprietary and the motherboard must support it. Here you configure both ports on the same network segment, but only one is used at a time. If the primary goes down, traffic is switched to the other. Usually these ports are cabled to separate switches.
I believe 2,3 are done at the driver level in Windows, so the MB NIC drivers must support it. 2 requires a switch that supports it. 3 doesn't require special switch support but can cause issues on some switches if Gratuitous ARP is not a part of the solution (HP for example).
Some misconceptions about aggregation are that it gives you 2+ Gig of bandwidth. This is true if you are running multiple connections, but connections are not split across the links. So, for example, if you are doing a large FTP transfer it would only be able to use 1 of the links. This is done to prevent packets being received out of order, which would cause re-transimissions/issues. Also it is doubtful a normal PC motherboard can fully utilize 1 Gig, much less 2 or more.
Basically, unless you are going to route 1.), the extra ports are pretty much useless for home use. It is pretty much a marketing ploy.