Detect Entity Movement

Is there any nice and simple way to detect an entity movement? Players have the event onPlayerMove but entities don't.

I found this: http://forums.bukkit.org/threads/tutorial-how-to-customize-the-behaviour-of-a-mob-or-entity.54547/

But I don't want to end up making a new class for each entity and having it break each update. If anyone has any nice ideas that will be great.

Also the reason I need this is I am trying to implement NPC vs mob combat. Easiest way to do that is to get some sort of event or something to see if a mob moves into a visible radius for the NPC.

Also how would I go about making an NPC jump? I am using the npclib to manage my npcs.