http://www.youtube.com/watch?v=o7HuJQjoyBY&feature=g-u-u&context=G27e9cf3FUAAAAAAACAA
fyi
Built something based on it in singleplayer. It's noice.
Except... Mine's better. It's a tad longer, and I discarded the lava spike in favor of a fall trap. Two main reasons - first, because I like getting ze spider loot as well, and second, because I made it a dual-purpose loot collector and XP grinder, by
almost killing mobs with the fall, then giving them a single hack to the shins to release their sweet, sweet experience orbs.
I'm rather fond of it. Now I need to enchant some schtuff.