I think this is one of the biggest ingame secrets/strange places in World of Warcraft right now, and if you haven't been there yet, you should travel there immediately! I can't promise you will witness the spectacular sight at your first visit, but it's worth coming back once in a while to see if things are happening…
The Whispering Forest is located in Tirisfal Glades in Eastern Kingdoms, just west for Deathknell, the Undead starting area, and you need to use a flying mount to get there. On the map this just looks like a mountain area with a lake, but when you arrive there is a small forest with mobs of level 80 + (although Tirisfal Glades is a level 1-10 zone). The mobs here are Tirisfal Stags, plague-infected Tirisfal Does and Tirisfal Fawns and a plagued bear. There is also critters/battle pets like rats and bats here.
Deathknell behind me, looking into the Whispering Forest
Stags, Does and Fawns live in the Whispering Forest
On the bottom of the lake there is a crashed plane with a gnome skeleton next to it.
The first Fey-Drunk Darter has arrived
Just fluttering around
Gathering around the Fairy Ring
And then the magic starts!
The music is magically beautiful, and the animated notes insinuate that they are singing
The forest animals are gathering around
And then it's all over…
I think this is one of those small things that make World of Warcraft such an amazing experience, this is what makes me wanna stay in Azeroth, even after many years! And I think everyone that is playing WoW, should seek out events like this, because it is pure digital magic!