Right rock method
Associated movies
In this method you bounce off the near right ledge from the V, then a rock near the Marines; or do a similar but harder variation using the lower deck and a more distant rock. Suitable only for PAL.
Full description
Get to the bottom of the V and face right. Run off the edge almost parallel to the cliff without much speed. Actually you can first move up the slope of the V a bit then just walk off, if you prefer. On the ledge below, there's a sort of chevron feature made from two abutting triangles resting against the cliff (see clarification pic showing the outline). They have a friendly slope and that's where you need to hit. You don't even need to crouch. Bounce off smoothly towards the rock on the near side of the Marine defence area. Crouch as you hit the rock on the side somewhere, and you can survive - potentially without even a flicker of your shield. Some rocks will be friendlier than others however (the rock will have been randomized last time you crossed a loading point).
The chevron is the key thing for this method, and it may be helpful to have a look at it from up close on the ledge so you know what you're aiming for. You could put yourself on the ledge using a stolen Banshee. You can also get a good view of it in BCM12 after 2:10, when I deliberately go back to show where I hit.
The easiest part of the chevron to hit is the nearest half. There's a dark streak along that triangle, easily picked out and useful for targeting. In falling to that area you'll probably find it best to be facing parallel to the cliff, as that makes it easiest to target the narrow triangle. However, you can really be facing any direction you like; it just might take a bit more finesse to hit the right area.
The other main option to coming down sideways is to have your back to the cliff. You'll need to be fairly close to the cliff, but unless you're going for the thickest part (near the apex of the chevron), you mustn't be against the cliff or you'll miss the chevron entirely. So, the thing to do is to try and drift slightly away from the cliff at the last moment. If you miss, you're likely to either die or have a juddering impact which leaves you without enough health to survive the rock.
The far half of the chevron is also viable for bouncing off, but your technique will need to be a little different and you'll need more forward speed to reach it. You can use that half to get yourself bounced back the way you came, to some extent. I make some use of that for doing 'stunt jumping' towards the end of BCM12.
A crouch can be used at the ledge to try and shorten the distance you end up travelling, namely if you find that you're tending to overshoot the rock; but it depends on quite how you're hitting the ledge. Normally I wouldn't be doing a crouch.
If you find that you keep ending up heading to the right of the rock, one cause could be that you fell to the ledge with too much lateral speed. As well as trying to keep your speed down, you could try to hit the chevron more towards the nearer end, where it's a bit thinner. I like to aim for the middle or just before, and I avoid crouching as I hit, else I'll tend to undershoot the rock.
As a harder variation of the method you can use the lower deck of the bridge as your run-off point, bouncing off the chevron (don't crouch) and then the further of the two rocks near the Marines (see picture), crouching as you hit. The rock will need to be relatively friendly however, and you can expect health damage. See BCM280 at 3:08 for an example.
Checkpoint advice
To make things as easy as possible for repeat attempts, get a delayed checkpoint when ready to start your run off the V.
Difficulty and system differences
Speaking as a PAL user I'd count this as one of the easier methods. Unlike others using the near ledge, there's no really tricky work with the controller. Targeting the near half of the chevron is hardly any trouble when done sideways on, and it's relatively easy to end up heading for the rock. Surviving the rock impact is somewhat of a lottery, but it's no great hardship to do retries when things are so painless in terms of controller work. It's a beautiful and satisfying descent when all goes well. In terms of success rates, I haven't done extensive testing and it would vary according to which rock you get, but for the triangular-shaped rock in BCM12 (also seen in the second picture above) my success rate seemed to be around 20%.
As for the variation in which you run off the lower deck and end up going for the further rock, that's harder and you'd probably need the friendliest rock to stand any chance of surviving. I had a success rate of around 10% with what looked like the friendliest. The impact always knocked at least four health bars off.
On NTSC and PC I believe you can bounce off the ledge alive, but would be killed by the game shortly before reaching the rock (near or far).
History and links
Chris Corelli described this method in the HBO forum on March 29th 2002. He didn't specifically mention the chevron feature I've emphasized in my description, but I think that's what he must have been hitting as it seems crucial. From his description it sounds like he was hitting near the apex of the chevron. But despite apparently being the first single-player method of descending just by good jumping, it seems to've been rather neglected compared to xbill's enthusiastically greeted method five weeks later. Possibly it was because he had no video or pictures to show, and also warned that the method was "VERY HARD", making it sound like a heck of a long shot - which it isn't really, once you've got a feel for it. People may have discounted it as impractical. Corelli's post got a few replies but nobody actually reported success. I feel kind of sorry for the guy. Seems to me that the method was a significant breakthrough and deserved a much better welcome.
You can see the method done various ways in BCM12, and there's also an example performed under Banshee fire in the second half of BCM13 (and I toast the pesky Banshee shortly thereafter, of course). The movies were advertised in the HBO forum here.
When finalizing the article (Jan 30th 2011) I came up with the variation in which you use the lower deck as the run-off point and end up heading for the further rock.