has anyone thought about putting a router inside of a case mod? maybe if you enclose the board and you have cables going out, so no one can see the ports you could have a 4 port setup on the back of a box. throwing out an idea so you can have more control over your other machines, and hide another unsightly box.

Whitlock, not a bad idea, you would need some sort of switch to power it on and off as well as easy access to the reset button. I have still, yet to find a router that didn't need restarting or reset every now and then. But not a bad idea

I may be misunderstanding what the discussion is here, but I haven't had to do a thing with my router.

I have the Linksys Etherfast Cable/DSL Router, Model BEFSR41. There are currently two machines hooked to it.

Rather than a router, I would use a hub, anymore, they are getting cheaper and smaller to the point where it would fit nicely on a 5 1/4" bay and you could easily run cable to the back of your case and have the ports on a pci bay cover. Also, thinkgeek.com sells a pci card that does what you looking for that can be found here http://www.thinkgeek.com/computing/accessories/5ad1/

is that mac compatible (the pci card)?

I've seen it done in some PC mods, There was one in Popular Science a couple of months ago, but I think its also on mini-itx.com.

As for the router vs hub, go with the router, since they usually double as switches, which helps especially if your network is going to grow (or if its going to manage a lot of bandwidth).Size isn't going to differ too much

Depending on how long you plan on keeping the computer running you could just add a relay to the Main PSU to control power going to the router/hub's power supply. It's a common idea in the Power CC ring.

I'm not entirly sure, but it may be, OS X supports so many things its not even funny, but I would definatly do some research on it before buying.

I was thinking about doing this as a small part of my Next Big Plan (notice the capitals). The Next Big Plan was to take a broken powerbook or imac (maybe one with a faulty analogue board), build it in to a rack-mount case and incorporate a hub. I was going to use the finished product as an NAT and file server. Needless to say this project is on the wish-list until I can find the right hardware. It might end up having to be x86 with Linux (gasp) unless someone has one of these machines broken in New Zealand.

I think the aim would be to plug the original computer's built in ethernet port in to one of the hub's ports, creating a machine with 7 Ethernet ports.

First.
It's more efficient to use a small hardware router for NAT. They make forwarding decisions at the hardware level, so therefore they can make them with less latency, and consume less power.

Second.
You aren't actually creating a machine with 7 ethernet ports. There is still only the throughput of one. Also, if you are doing major file sharing, you will run into collision hell if you're using a hub.

In sum:
Don't use software NAT unless you really have to.
If you have a lot of traffic from multiple nodes, don't use a hub unless you really have to.

if anyone wants to know why i chose a router as opposed to a hub or switch here is why:

a router has a configuration you can change, especially a linksys commercial router (or if you're loaded a cisco). with this you can do administration.
with a router you eliminate haveing another box outside, as to hide it it. with this in mind, if you sheath your cables together, you could have a really slick looking configuration.

i am really glad everyone jumped on this idea! and i would love to see some screenshots if someone ever does this mod