I just cut-and-pasted the titles of the books I have out of the library into a tag cloud website.
Here's the list of the words most frequently occurring in the titles of books I currently have checked out: Ape body brain category center children cognition companion conscious consciousness creativity culture education experience group history intelligence language learning life memory mind nature neuropsychology social society status stress tacit talent technology
In the actual visualization, the biggest words (meaning most frequently used) are brain, cognition, consciousness, memory, mind, sciences.
On delicious (where I am less faithful user than I should be), the top tags are brain, learning, internet, attention, collaboration, games, evolution, digital.
But those are tags I generated myself. What does this illustrate? I could speculate but there's a louder voice whispering in my other ear: "Ok, Cat, you are procrastinating enough. Back to writing!"