1. "Nothing Else Matters", Metallica
This is in my opinion one of the most hauntingly beautiful songs I have had the pleasure of hearing. It is deep, harmonic and the lyrics are moving and true. The perfect song for singing along to when there is no-one around to hear the emotion in your voice.
2. "Bad Habit", the Dresden Dolls
I didn't actually like this one until I had sat down and listened to the lyrics. I adore those kookie songs which sound so joyous, so triumphant, so full of rapture... and yet are about something darker, colder, more sinister. Much like "Kommsusser Tod (Tumbling Down)" by Sagisu Shiro of Neon Genesis Evangelion fame
3. "It's No Good", Depeche Mode
I'm such a tragi-goth. A deeply sensual, seductive song with a back-beat to die for and a melody which swallows you up. One of my favourite clubbing songs.
4. "Ship Song", Nick Cave and the Bad Seeds
If ever there was a song to get drunk and weepy to, it would be this one. In fact, I have gotten drunk and weepy to this song on many occasions. Another one to belt out at the top of your lungs, if you can manage it.
5. "Meet Me in the Red Room", Amiel
It's cheeky, it's sexy, and it's fun. It reminds me of strip-teases and burlesque, and I adore it in the right circumstances. For those who don't know, it is the song that plays during the film 'Moulin Rouge' when Christian is first taken up to the elephant.
6. "Add'ua", the opening song from the console game Tenchu
It's not quite classical music, so I think I can get away with it. It is a song which starts off slowly, quietly, with a very Japanese feel (as, you know, it's from a game all about ninja), but builds to a more... I don't know, 'pop' kind of a feel. It's ever so dramatic and exciting stuff though, as game opening music is supposed to be.
So, there you have it. The first six favourites which came to mind.