I just found a german social network ranking which was built with www.seitwert.de a nice tool SEO check tool. I alread used such a page last year but forgot the name, it was something like Egometer or so.
On No.1 as expected www.xing.com, no2 www.studivz.de and no3, i never heard of… www.spin.de
Read the complete list at seitwert or at the german web 2.0 blog zweinull.cc with an analysis.
Of course
I just checked my own blog and all the other pages like this or this or this or this
And according to Alexa.com my blog is up to place 500.000something from no 2,100,005 last month, not bad but still not very satisfying.