Hard to believe – but in fact you risc a civil penalty of up to 10.000 EUR, if you don't give a copy of your web sites, blogs etc. to the German National Library (which applies to sites in Germany only of course).

See more at http://www.heise.de/newsticker/meldung/90316 and http://bundesrecht.juris.de/dnbg/__19.html.

Though the German National Library will propably not take any legal proceedings in this case, since it was realised, that it does not make sense, to collect any online available content overall.