I downloaded and give a try at this map http://www.planetminecraft.com/project/herobrines-return-15-minecraft-adventure-map/ You won't beleave what they did :O I was so exited when I fist time played this. There is GUI of "Souls that you have (calculated with XP) and everything is so Configed. ALL mobs have armor, There is Mob on Mob standing, There are Virtual people that are shooting rockets with Explosion effect. Woow , NO MODs! VIllagers are speaking to you. Its so AMAZING... Anyway. You won won't belive you eyes. Now I thought that was possible in 1.5, So is there any plugin that can do even something like that what they did?
Mizquink Test what? Majority of the features that the OP talked about aren't accessible right now in Bukkit.
As far as i know... Most (if not all) on Herobrines Return (I also played this with friends, Loved it) Was done with Command Blocks Commands (Scoreboard [That GUI, Souls] stuff, TP, NPCs Talking, Probably used to make NPCs [look] like they cast spells using firework Effects) And NBT Editing/MCEdit To make mobs with armor, Drop rates Special Trades with Villagers, Custom Enchant Levels, Item Renames. All that good stuff. As for a plugin.. im sure ALL of this is possible EXCEPT for the "Souls" GUI Thing as of Bukkit Build 1701 Bukkit has yet to add the new commands on 1.5 (The new GUI thing comes from the Command /Scoreboard)