Gerald has a good Moondog page and has given me some good information. It has links to other pages and record buying info. Also some great stuff from Psychedelic Folk Music to Earth-Music from Poland and everything in-between. Well worth checking out.

Moondogscorner An extensive German site from Uli Schmidt

Interview with Ilona Sommer his partner in Germany, although the page is not always available. You'll need Real Player to hear it
There's also a text version

Interview with Moondog

Moondog (1916 - 1999) a Portrait by Kenneth Ansell