I've got a long and lulzy list. I'll start off with the must unsuspecting.
Tsurupettan
http://www.youtube.com/watch?v=hfUe2eckPFQ
This song was the entrance to my kawaii uguu animu narutard hinata is god stage... or at least part of it. A great asianese children's song about stalking and small boobs. And perverts. Dafuq did I do to myself 3 years ago?
Caramelldansen (in just about any form, really)
http://www.youtube.com/watch?v=lHBUcnIW_Oc
Another kawaii uguu animu narutard hinata is god song thingy. I find myself doing this dance occasionally at marching band events whenever a cadence is done. It's also swedish or something. These three guys made a metal cover of it and it's sexy as heck.
Bad Apple (something from Touhou)
http://www.youtube.com/watch?v=VzEUeWnV73U
You might think this is a kawaii uguu pop-rock animu song about princesses and fairies, right? Wrong. This song is about very powerful little girls killing each other in the name of war and madness, and the lyrics are about both falling asleep and never waking up and/or waking up only to die right after. Yes, it's an upbeat song about depressing ways to die. Ain't that nice?
Next on my list, songs that are just truly epic.
Aces High - Iron Maiden
http://www.youtube.com/watch?v=ohtXbvrHWqU
Probably one of the first Iron Maiden songs I ever heard thanks to Carmageddon 2. Also, probably one of my favorites. I always loved it as a kid even though I never really understood why it's so awesome, but now I do. And yes, the video I've plugged in is a Claymore AMV. Because Claymore is pretty awesome.
Tribute - Tenacious D
http://www.youtube.com/watch?v=_lK4cX5xGiQ
This is not the greatest song in the world. This is just Tribute. Seriously. I didn't know music could come this awesome.
Now to songs that simply... scare me. They just scare me.
Lavender Town (RIP Kossokei's pokemon blue)
http://www.youtube.com/watch?v=JNJJ-QkZ8cM
I remember the first time going to Lavender Town on Pokemon Blue. It was probably midnight, I couldn't see my clock. I was playing on my GBA, earbuds plugged into it. Lavender sounded like a fun place to go to. And then I had nightmares.
Lavender Town Dubstep - Solkrieg (I dubbed the song 'Dear Cubone')
http://www.youtube.com/watch?v=ywU2praUoYE
Probably the song that introduced me to dubstep. The feeling of this song... It's like being slowly eaten by a behemoth of ghostly proportions... it allows my mind to wander past reality and into my dreams, searching for some sort of meaning in my nightmares. It's also pretty sick.
U.N. Owen Was Her? - Flandre Scarlet's game theme
http://www.youtube.com/watch?v=8jJZA-O_B78
All of my fears. Flandre Scarlet. It's a sort of uneasy theme especially when you know who's theme it is.