I just discovered this stuff. It is PVC and comes in UV reactive blue,red,green. It is designed to prevent kinks in a H20 cooling systems tubing, but will work on any wire of the same size or smaller. It was $3 US for a 40" piece from SVC.com I am not sure if I am going to use the stuff in project Blue_Monday, but here is a picture. MS http://server6.uploadit.org/files/jeffrey9-coolsleeve.jpg
You can get this stuff in the UK, they're called chameleon springs. Yeah, they come in solid colours too! Here! HTH