this list of the twelve "top" skyscrapers in the world. I'd assume that by "top" they mean by height. They're also including a few skyscrapers that have yet to be completed.
The list doesn't name the structures, so let's try to do it here:
1. Eiffel Tower, Paris
2. Burj al Arab, Dubai*
3. Jin Mao Tower, Shanghai (thanks Fargus!)
4. Sears Tower, Chicago
5. Petronas Towers, Kuala Lumpur
6. World Financial Center, Shanghai*
7. Taipei 101, Taipei
8. Twin Towers of Canton, Guangzhou (Canton), China*
9. Freedom Tower, NYC
10. New Tokyo Tower, Tokyo*
11. Burj Dubai, Dubai*
12. Bionic Tower, Shanghai*
That's all I can name off the top of my head. Anyone? Link
The CN Tower in Toronto, Canada stands 533m tall. It will soon be shadowed by a few of these new ones but as of now, it's numero uno.
And not even on that list! Gaaah!
This link appears to be the most accurate list I've found on this subject. Wiki. Figures.