I wrote about Los Angeles PL's California Fiction Index for lii.org a few years ago. Today I ran across another great index they've got going -- the Serials and Sequels Index .
"A listing of fiction books for adults which are part of a series, or are sequels to earlier novels. Can be searched by author, title and series name or characters."
This joins the teen (Bettendorf, IA) and children's (Mid-Continennt, MO) series and sequels indexes maintained as library information services available not only to their communities but to anyone, from the web. I like to think of these as 21st century library services.