OCLC's Worldcat has begun a new service showing the most important bibliographic information about any author - the identities series. Here is the entry for Twain showing the books by and about him from the beginning: http://orlabs.oclc.org/identities/lccn-n79-21164 I've also just learned this week that as a part of the settlement with the publishers and authors, Google Books will allow every public and university library in America to have one machine that can access about 5 million books that are in copyright but out of print. What an age.