• AngryAnt have made two fantastic additions to Unity which are exactly what you are looking for. These are Path and Behave and can be found on his site.

• Aron Granberg have made an impressive A* path-finding system, that scans the surroundings automatically.

• UnityWiki A* example A barebones textbook implementation of the A* method. Should be very easy to add and adapt to your project.

Try to do a search on the forums for the usage of them.

Everyone, please add to this post (because it is marked as community wiki), this way all examples will be in one place.

There is another one too, it is acctually my own pathfinding system which can be found on my website here: http://www.arongranberg.com/unity/a-pathfinding/ You can download an example project and the full source there.

I don't know about any enemy script tools though.

SimplePath just released this week: SimplePath

And here is the forum thread: SimplePath Official Forum Thread

http://blogs.unity3d.com/2011/06/16/unity-roadmap-2011/

Pathfinding is listed for Unity 3.5.

I figured this may help: xaitment recently released a set of Unity Plug-ins based off their successful xaitMap and xaitControl products. xaitMap and xaitControl for Unity can both be downloaded and evaluated here: http://sites.fastspring.com/xaitment/product/main