Not satisfied to just entertain the masses with inane Vampires and SuperPokes, the social-networking site unleashed Lexicon on users this week.

It’s kind of like Google Zeitgeist except… well, it is exactly the same concept, all part of Facebook’s admiration of Google (GOOG) things, like, for example, as many of its employees as it can entice away.

As Facebook’s Roddy Lindsay described it: “We thought it would be cool to show trends on the public and semi-public forums across Facebook (also known as Walls). Today we’re announcing the launch of Facebook Lexicon, a tool where you can see the buzz surrounding different words and phrases on Facebook Walls.”

But, as much as I hate a lot of these juvenile time-wasters online, I do like the very simple Lexicon very much, especially in its ability to compare up to five keywords or two-word phrases at once.

Thus, BoomTown is periodically going to post word comparisons here, always using Britney Spears as the control word, since she has been a perennial champ on Zeitgeist for a very long time.

So, today, it is presidential candidates–Sens. Hillary Clinton, Barack Obama and John McCain.

As you can see, among users of Facebook, Britney holds up surprisingly well, even though she is going through a quieter, less-manic-head-shaving period of late.

(Click to make the images bigger)

Please see this disclosure related to me and Google.