I look at my LibraryThing clouds only once in awhile. My Tag Cloud interests me the most for my profile. I like to see what type of genres that have interested me and the larger tags are very reflective for what I usually read.
I took a look at the Common Knowledge Clouds for All LibraryThing (far right link on your clouds menu bar) and what struck me was the largest tag for Top 200 Most Populated Series was Harlequin Superromance. This tag must be popular because of all the libraries that use LibraryThing. Star Trek was another tag that stood out.
Here are some more facts about the All LibraryThing Common Knowledge Clouds. London and New York are the most often mentioned cities in books and where most authors live. Most Authors are buried in the Arlington National Cemetery in Virginia. "The Doctor" is the most popular character name tag. Most Authors were educated at either Columbia, Harvard, Oxford or Yale. Most Authors on LibraryThing are American in nationality. World Wars I and II are the top mentioned events in works.