What are the bussiest websites in Germany (traffic and unique users),
other European countries also have my interest

Interested in Danish sites?

1. Google: google.de 
2. Ebay: ebay.de
3. Google: google.com
4. Wikipedia: wikipedia.org
5. Yahoo!: yahoo.com
6. Spiegel Online: spiegel.de
7. Gmx.net: gmx.net
8. Amazon.de: amazon.de
9. YouTube: youtube.com
10. Microsoft Network (MSN): msn.com

somewhat surprising, that most of them are english language sites.

The exact details, can be found at:
http://www.alexa.com/site/ds/top_sites?cc=DE&ts_mode=country&lang=none

Here you will find the top 500 of all individual european contries, as
well as a the global top 500. By going onto site details you will be
able to access all the sites details and stats, which of course vary
from month to month.