Here's the top ten that I can think of at the moment (Trust me, I have many more favourites), not in any particular order. Hopefully my list adds some wicked variety to this thread  .

"Time" by Pink Floyd
"Cinnamon Girl" by Neil Young
"Van Helsing Boom Box" by Man Man
"A Liar in Texas in a Green Room in Memphis" by Capgun Coup
"Commissioning a Symphony in C" by Cake
"Time to Pretend" by MGMT
"Talking S*** About a Pretty Sunset" by Modest Mouse
"Little Wing" Stevie Ray Vaughan's version, but Jimi Hendrix's is pretty sweet too
"The Clap" by The Unicorns
"Hello Operator (Please Give Me #9)" by King's Horses

I have to say, Hiteryan, I like that second idea of yours a lot (don't get me wrong though, the first idea is pretty solid too), but I have a response to what you said here...

Now, either this special event would last for a few days, and then the mountain would sink back into the ocean, or this would just be for the really strongest players, and the mountain would just stick there forever.

... What you suggested, with the town and the spiral mountain, sounds more like a continued quest than a special event. If you want me to explain why I feel that, you'll have to wait a day until I'm in more of an explaining mood .