I finally decided to register at a Dutch site that attempts to bring together old classmates online. The user interface is a bit cumbersome and it took me some time to figure out how to edit a wrong entry. I am still not sure about one school. I copied the start and end year from a classmate, but I am quite sure he got it wrong.
It was nice to find out that one classmate now lives in Costa Rica. Another classmate, from the University of Utrecht, is an author of computer books.
However, in order to contact classmates you have to pay a fee. I put in my personal description that people can find out more about me by entering my name in Google. Of course, putting an email address or a link in your description is not allowed.