So with the new AI for hostile mobs I found that you could use it against them with some simple mob traps. I thought of these on my own but I wouldn't be surprised if someone already thought of something similar.
I haven't researched their AI at all but so far skeletons seem more intelligent then zombies, meaning that you'll end up with skeletons more than anything else.
This one is the easiest to make and least resource demanding of all. The mobs will seek shade provided by the blocks above the hole and fall in.
A 2x2x2 space enclosed by walls on all sides except for the entrance obviously. This one requires more blocks than the red one but is so far the most successful design of the three. When spawned in the middle of the three traps skeletons went to this one most often.
This one is be good for covering large spaces of land I imagine that if used in a plain or desert you'll have the best luck with this one. This design however seemed like a last resort for the mobs surprisingly. You'd think that if you were on fire you'd seek water rather than a shady place. So if you do use this one remove any shade they can hide in.
Just a note, the mobs that you do catch will have taken different amounts of damage from sunlight so it's impossible to make a reliable xp grinder out of them.