I found myself having to keep my eyes glued to my minimap to find rare creatures on the Timeless Isle. Thankfully, there is an event that is triggered when an icon appears, so I made a simple addon that triggers a raid warning when a rare appears.
http://www.wowinterface.com/download...RareAlert.html
Edit: And apparently it works for other rares too! It just popped up for a Zandalari Warscout.