I thought the intro music to the Witcher2 was incredible - a powerful vocal, with a real fantasy feel - and wanted it in Skyrim. I use it with Brumbek's spinning logo animation, which is cool.
http://skyrim.nexusmods.com/downloads/file.php?id=7801

NOTE ** - to all who downloaded the file I uploaded previously - i'm sorry about that!
I zipped up the original wav instead of the converted xwm. I was tired, with a few beers in me. What can I say??

Anyway this is the CORRECT file.

To install:
1. In your Skyrim/Data folder, make a new folder "Music."
2. inside music, another new folder "special."
3. Extract the contents of this zip, then cut/paste 'mus_maintheme.xwm' into the "special" folder.
4. Turn speakers up loud and enjoy!

To uninstall:
delete mus_maintheme.xwm

I have no way to test this on anyone else's setup - but I can't really foresee any problems. If you have a mod that affects menu music in some way you might have some grief - but you're on your own there.

credits:
None to me, the conversion took 5 seconds.
- the band, who can be found at
http://www.zywiolak.pl/en/
- vikichan as I used MultiXwm to convert
http://skyrim.nexusmods.com/downloads/file.php?id=3159
Bethesda for another righteous game.

Cheers