Warning This will not work with Gigabit networks, however if its for home use you probably don't need to worry.
(Bear with me this is my first instructible)
Other than video and audio you can adapt this to run a number of things. When used with a telephone line, it may be referred to as a 3 pair or 4 pair Voice/Data cable.
Now about the parts you'll need. You can of course throw something together by splicing wires, but i decided to go for a cleaner look. As you can see from the pictures below.
I used these items which can be purchased at your local Radioshack or parts store
(Note: this is just for one end of the cable)
1. Project box from Radioshack (Altoids tins work as well, its easy just to ground everything to the case)
2. 3 Phono Jacks (They come in packs of 4)
3. Ethernet Cable
4. Soldering Iron
6. RJ45 Crimp tool (optional)
7. RJ45 Jacks (optional)
8. Housing of some sort (I used a "Shack" project box on one end and metal mint tin on the other)
6 and 7 are only if your making the cable, you can also just cut a cable near the end and use that. It would probably be easier for most people. However this project is geared toward people who have a crimping tool, because I used one. I will do my best to describe what non-crimpers should do, I'll try to do one without crimping soon so I can get some pics.
Just letting you know you might have to improvise some on the box, but I have found that just wrapping it all in electrical tape will work. Just make sure the wires and Jacks are insulated.