There's another group, based in Netherlands, "Vrienden op de Fiets" or "Friends of the Bicycle",
www.vriendenopdefiets.nl. The site has a page of information in English, and, I sent off for information about joining. I hope I can get signed up in time for my trip.
BTW, I took deerhoof's idea and we're staying at the hostel he recommended. It will be convenient, as, I think we'll be in Amsterdam before we can get into a room...at the hostel, we can stash the bikes and our gear in order to do some site-seeing.
Keep the recommendations coming, because, once the search engine is up and running other people will be able to search and benefit from your experiences/information.