I have already spliced in to the cigarette socket 12v ignition live for my new HU but now I am in need of another switched 12v source as I want to wire up a camera and LCD.

There's a camera and a small LCD that both have a ground and a live wire but can I somehow join them and just bullet them in to one wire each rather so I have 2 wires instead of 4?

Where is the next best place to go?

http://pages.ebay.com/link/?nav=item.view&id=251481810793

This might do the job...

No need to splice your cables just plug into an existing fuse socket then find a ground you can connect to, then you end up with both the new accessory and the original circuit protected.