Illustrated Quixote is a Brown University Library digital project--one of many inspired by the 400th anniversary of Don Quixote in 2005--that allows you to search/browse and view illustrations of Don Q produced between 1725 and 1884. There are a number of other excellent sites devoted to illustrations and paintings of the novels, as well as to the publishing history of the novel itself, notably The Cervantes Project, OSU's Digitized Historical Editions of Don Quixote, Georgetown U's Tilting at Windmills, and the Don Quixote de la Mancha digital exhibit.
The Reading Experience Database is collecting information about 'what British people read, where and when they read it, and what they thought of it' between 1450 and 1945. You can sample the database by searching for reader responses to (e.g.) Shakespeare or Dickens or Karl Marx, or to newspapers in general. It's a collaborative project, open to everyone, so why not contribute?