After adding little things one at a time to the interior including gauges, switches, audio equipment, etc., I found myself in a mess of wiring. If you find yourself in this poistion or plan on adding a some electric gizmos to the inside of the car, this is a good solution to use to keep wiring easy to deal with.
This is what I used to provide easy connectivity.http://www.radioshack.com/product/index.jsp?productId=2103230
I used 12gauge color coded wire to connect all the terminals together (into 6 negative and 6 positive). This style accepts bare stripped wire at a wide range of gauges and tightens by flat blade screwdriver so a dummy can do it. You can bolt it to the car if you wish but 3M double sided tape or trim tape will do wonderfuly and without putting hols into anything.
mounted and powered
That's basically put all together except for the three gauges that go right there and that's what all the wiring laying about is all for.
The main + power wire supplying this is a fused wire from the ignition and the - is a chassis ground supplied by a bolt just to the left of the center counsel, right above where the drivers right knee would be while sitting in the car.
All the components that this terminal strip feeds are very low amperage loads. I wouldn't suggest putting anything very high draw on this type of arrangement. The biggest load I have on this is my electric cutout and that has never blown my 25amp main fuse while in use with everything else on at the same time.