This update is an interesting one. My skeleton spawner trap has suddenly become even more overpowered thanks to the addition of bones. Instant arrows, food and wood? Hail to the king, baby!

My attempts to rebuild the drowning trap with a different design (raising the mobs to a more convenient level before drowning them) have been thoroughly unsuccessful because they wouldn't sink down again for some reason, but just now I've read that I need to use glass for the downward part like I did on the simpler first version--water that's touching by glass has more downwards pressure than water touching other block types.

Actually, I've been using wool for walls and floor tiles for a long time now. This gives me many more options in that regard.

Also worth noting is that it's best to apply dyes to the sheep, not the wool itself, since a sheep can drop up to three blocks for a single unit of dye.

Spiders can only climb vertically at the moment, so a single-block overhang around the edge should be able to work (unless the spider can leap onto your location from somewhere else, of course).