Hey today I was just derping around in the nether and created a little mob trap with lava and water. It works pretty well actually, you can try to find it on live map of smp6, but for in-gamers just go east of the spawn, stay around the main flat ground, and keep running to a 3 block wide tunnel. You should find it. For those wondering how to place water in the nether, get a silk touch pickaxe and break ice, and then place an ice block in the nether. Or just buy some ice, then break it. where you break it is the source block.