I bought Where Late the Sweet Birds Sang, but alas I've not yet read it. Likewise, A Case of Conscience. I recently tried to read A Fire Upon the Deep but gave up after a few pages. As with The Gods Themselves, I was bored by the aliens. (Perhaps the aliens were written rather too well - so alien that the struggle to understand them removed a great deal the pleasure of reading the book!)

I might also have The Moon Is a Harsh Mistress, purchased sometime in the last year, but also unread...So many books, so little time!