_NPCScan is an addon for finding super rares. As you’re flying around the world your internal cache automatically updates with a list of all of the mobs you toon can “see”. When your cache “sees” a rare mob, NPCScan notices and sounds the alarm. It plays a distinctive sound and show a clickable picture of the rare at the bottom of your screen. Clicking on the Rare’s nameplate causes you to target that Rare.
While flying around in Icecrown on Sunday NPCScan went off and told me it had spotted Putridus the Ancient. I clicked on the name plate and then spun my camera around for a few minutes looking for the mob. It took about a minute, but I finally located him. Two of my guildies came and helped me to down him. I’ve now gotten 3 of the extremely rare mobs for the Frostbitten achievment. Oddly, you can also spot Putridus while sitting in Dalaran 
He pats that close to the city.
While looking up info on NPCScan for this post I stumbled across NPCScan Overlay. This is a helper addon to NPCScan that draws overlays on your maps to help you find the super rare spawns. I haven’t installed it yet, but I will this evening.
After you’ve spotted a rare, if you want to be able to spot it again you’ll need to be sure to clear your creature cache. The addon page on Curse.com has good instructions about how to do that.
This addon is perfect if you’re looking to complete the super rare’s achievements.. or if you’re a hunter looking for that rare pet.. or if you want that lovely drop (Time Lost Protodrake)
Nice! I have been running NPCScan for several weeks now, but have only found an already dead BC NPC. I look forward to trying out the overlay addition, which looks to work with Carbonite.
Thanks!
Elkagorasa´s last blog ..Dead Man’s Party
Note also that it has automatic false alarm detection, so you don\’t get excited when some hunter is sporting an un-renamed Gondria in Daleran. Very useful for keeping your hunter from having anxiety attacks on a regular basis.
I have been running with this for a while now. I like it.
Only issue I have is that the the image and name box (that you have pictured) Is not movable. At least I have not found a way to easily move it. I may have to mess with some code.
Thanks for the overlay tip.
Hydra´s last blog ..It’s 9 PM, Know Where Your Mother Is?
I tried to use it for about 2 weeks. After stumbling onto my 15th rare spawn with no alerts from the addon at all I deleted the thing.
I love to hunt rare spawns just because I want to kill every one in the game. I got the addon hoping that I could find them all a bit easier, but it didn’t happen.
With how many other people I see still talking about using I must have been doing something wrong, but I never got it to do anything for me.
Psynister´s last blog ..Did you lose your pen, Psyn?
The important thing to remember is that if they’re in the cache when you install it, you won’t ’see’ them. Install instructions should include “Delete the cache now. Just do it.”
Not saying that is the cause of the problem, but based on what I have read, that is the most likely culprit. Hope it helps.