Shelfari has posted images of Neil Gaiman's library. They're numerous and large enough that you can zoom in on the individual titles that he has shelved (or not shelved as the case may be). I've seen large home libraries before. I've seen extensive author's libraries before. This is the single largest private library that I've ever seen. Here's a quick sample that doesn't even begin to cover it:
There's just one more thing. The library that Shelfari has the photos of? It's his downstairs library and he keeps the reference library upstairs.