This isn't necessarily a linux question, but here goes.
My internet connection right now is through a dorm, so when I jack my computer into the wall, I can see all of my friends on the network. I'm behind a router though, and thus on my own subnet. What I want to be able to do is use this computer (behind the router) to view the network like it would if it were jacked into the wall instead of the router. Is there any possible way to do this?

Oh, and by view the network, I mean like if someone was hosting a network cs game (rather than internet game-you know what I mean) I could see that because i was on the same network.

What is this router you are behind of? A linux computer or some cisco or smc router box?

If there is eough ip space available on the better side of the router (the outside), linux can be configured to work as a transparent ethernet-level proxy, where linux computer acting as a switch or hub (this is called bridging).

If this is what you want, see Adv routing howto on how to do it. More often what is wanted is using linux a firewall to isolate intranet from the others and do a few portholes to access things here and there and to occasionally look like a frontend server.

I'm behind a linksys wrt54g (or something like that), and I'm going to set up routing on my linux box and just use that as a hub and wap. I want a linux router so that I can have more control over my network.
I only have one IP address for this line, so I can't deliniate my own IPs on the network

If you have only one IP address you can use in the outerside of the router, then bridging is not what you need. Search for 'nat' (network address translation) and 'linux router' on discussion on how to configure such a thing. (Either from this forum or the internet)