Word Clouds

Blog Word Clouds:

13 Things Word Cloud

Running Down The Dream Word Cloud

Both word clouds give insight on what the blogs entail.  For instance, with the 13 Things Blog the words chosen deal with Web 2.0, while the Running Down The Dream Blog the words are all related to running.
With the 13 Things word cloud the words most prominent are word, on-line, Google, vocabulary, thesaurus.  The other word cloud dealing with running the most prominent words are running, runners, shoes, foot, train.  
This visual representation of words acts like a summary of what the blogs are focused around or what the main topic is all about.  A person visiting these blogs can simply check these word clouds and get a quick glimpse of the entire blog as a whole.
This seems to be more of a fun toy and I wouldn't expect this to be used professionally unless one's profession deals with creativity like an artist or creative marketer.  Word Clouds also can be used as a motivation tool by inserting words which raise moral within a company to get them all fired up, too.