Go to the Russian countryside in Destiny. Head left past the plane graveyard, through the building where you first encountered the moon-wizard, and out the back. Hear that gunfire? A handful of high-level players are probably standing there, shooting at a cave.
They're shooting at the cave because if you do that for even a little while, the cave winds up looking like this:
Yes, this is the latest technique for farming in Destiny, and it's by far the most effective I've found. Spend an hour or at the Murder Cave and you'll get so many engrams that you'll almost surely get something you want. You don't even have to shoot a single enemy — loot spawns if you're in the vicinity, so your neighbours' kills still give you loot.
If you're lower level, you'll generate XP very quickly, even if your loot drops aren't that exciting. Valleywag's Sam Biddle hung around the cave with me and Jason last night and went from level 16 to level 18 mostly by sitting around, cracking jokes, and occasionally shooting things.
The technique, as shared in this video by Force Strategy Gaming (thanks BlitzKaiser!), has become so widespread that I've yet to go to this area of the Cosmodrome and not find at least one or two 24s or 27s sitting out there shooting.
The rules are simple, and agreed upon: Everyone stands behind the rock slab, everyone is sure to kill all of the hive thralls and acolytes before they get too far (if they escape, the constant spawning stops), and everyone takes periodic breaks to run into the cave and gather loot/ammo. It's kind of beautiful, really.
If you're down in Russia this weekend, it's worth swinging by just to see everyone working together so effectively. Might as well stick around to get some loot, too.