Try the Virtual Library for lots of subject oriented links, such as Museums. One of my favourite is the Museum of Paleontology in Berkeley California.

For a list of libraries and library resources go: The Libweb Library Server.

Make sure to look in at the biggest and best library in the world: the Library of Congress in Washington, D.C., where you will also find the Smithsonian Institute.

Or stay close to my home and visit the Royal Library at The Hague.

Public libraries are also not to be ignored. Visit the Internet Public Library. Or look for a library in The Netherlands at the Bibliotheek.nl (Dutch only).