I can think of very few times when a word spider is what I would need when looking up book titles. In theory, I can see that it might be useful for accessibility of various sorts, whether for people who think in synonyms or English language learners, or people who are generically searching by topic instead of by book. I wish I knew if it was actually going to be useful enough to devote that much of the visual catalogue space to.
Speaking of book-related puzzles, if you would like to try winning seven science fiction books (six of which would be the books you guess, the seventh a forthcoming anthology of original short stories by lots of people you've heard of if you read much contemporary SF), go enter the contest over at Torque Control. It's only running through Wednesday. To enter, you need to guess the six books which might form the shortlist for this year's Arthur C Clarke Award from the list of eligible submissions and post that list in a comment in reply to this post.