bbc.co.uk, ABC and Lists
My colleague; Helen Lippell has written a piece for the Information Architecture journal; Boxes and Arrows outlining the work and preparation that helped her overhaul bbc.co.uk's A-Z tool,
"repositioning the site index as a viable secondary navigation tool." (next to Search).
The re-architecture of the A-Z last year substantially improved the findability of content around our rather complex site and Helen has put together an excellent summary of why this service is an integral part of our network. She also has a good anecdote about the Grand Vizier of Persia.