I finished Buddenbrooks a couple of weeks ago and am still mulling over bits of it and thinking about it intermittently. It was a wonderful, wonderful novel: I loved the way the historical change of the nineteenth century was shown, even though the novel never steps outside the immediate circle of the Buddenbrooks family, and the way that he talks about teeth all the time (I read somewhere that this was his attempt to mimic literarily Wagner's musical use of leitmotifs). I love the incredibly detailed descriptions of people's appearances and also the quiet, detached, ironic tone. 
This has prompted me to start reading Marcel Reich-Ranicki's Thomas Mann and his family, which has filled me in on what an insane egotist and neurotic Thomas Mann was. I'm never sure how I feel about this kind of literary gossip; there a part of me that feels that you shouldn't concern yourself with what an author is like, but with what he writes. The Heat reader manquée in me loves all the gossip and the details of the nasty letters Thomas Mann wrote to his brother and the insanely self-obsessed diary entries, though. 
Incidentally, Wikipedia has given me a link to the FBI's file on Thomas Mann. Which other writers are there with publically available files?