RLJ (Red Light Jumping). (The definitive bikeradar thread)

Of course, but the main reason why so many people do it now is because it has become so easy at the aforementioned type of junction. (There are also a number of less important reasons.)

I don't agree; there are more cyclists and there is a lot of monkey-see-monkey do. Same reason cyclists think going up the left of vehicles at junctions and always trying to get to the front is what they are meant to do, or can get away with. You watch a bunch of cyclists stopped at a light; as soon as one decides to jump it others follow. It becomes a habit, it's easy to get away with (which may account for the sense of unfairness cyclists express when they do get caught) and the perceived benefits (which I think are actually usually retro-fitted to the behaviour) are rarely scrutinised. There's nothing odd about it, people generally get away with whatever they can get away with as long as they can find some 'convincing' reason why it is ok for them to do it.