I stumbled across an Alan Turing website managed by Andrew Hodges, a biographer of Turing, author of Alan Turing: The Enigma. The site has wonderful material on Alan Turing.
I read Hodges' biography many years ago and enjoyed it. If you found the 600 page not sufficient, this site provides goodies like pictures and lots of details that didn't make it into the book. A "must see" is the Alan Turing Scrapbook.
As well, the site has a number of articles and papers on Turing. I particularly enjoyed Turing: A Natural Philosopher. Hodges has made this book available in an on-line version. Very nice.
If you want the gory details of how the state hounded Alan Turing, one of the greatest minds of the 20th century, to his death, watch this...
If you want to see a video where a professor tells his class why Turing was so brilliant. In 25 minutes he does a fairly good job. He's a little fuzzy on details and is dodgy with minor factual slips, but the basic message is correct and makes it clear what Turing did. And he conveys the excitement of the genius of Turing:
If the above video boths you with its rough edges, here is a nicely polished 7 minute version of Turing's importance. This is nicely polished video: