Cricket

Meaning: My favourite thing, but if you'd like a longer definition, the online Oxford says:

an open-air game played on a large grass field with ball, bats, and two wickets, between teams of eleven players, the object of the game being to score more runs than the opposition

Usefulness: 1 (if you talk about it as much as I do. I'm rather impressed I've done 77 posts without mentioning it here.)

Logofascination: 2 (etymology unknown, and about as many theories as people to ask: the Inky Fool talks about a possible connection to stool-ball, wiktionary features someone else's theory about Dutch origins, and there's a bunch more theories over at wikipedia.)

Sternomancy

Meaning: fortune-telling by the breast-bone, or 'markings or bumps on the chest or breast bone'.

Usefulness: 3 (One could use it as Rabelais does, to remark on the size of someone's stomach, or to describe some of the measurements they do in gyms and doctor's rooms and things; they are supposed to be predictors of the future, one way or the other.)

Logofascination: 3

Natatory

Meaning: as a noun, this means a place to swim (generally a pool of some kind, although not always) and as an adjective it applies to things of, or relating to, swimming.

Usefulness: 1 ("Out the back we have our humble natatory." "Urquhart Bluff Beach* seems natatory, but has some dangerous rips." And then there's all the things it could have been applied to during the Olympics: "A dearth of medals natatory has disappointed the nation.")

Urquhart Bluff Beach: not natatory.

Logofascination: 1

Hippodramatic

Meaning: the dramatic arts associated with a circus; the drama of a circus.

Usefulness: 1 (This word suggests hysteria and bathos and a grand fuss. Asking someone to stop all the hippodramatics, or describing an event as terribly hippodramatic, is self-explanatory.)

Logofascination: 2 (Despite the hippo-, this doesn't seem to have arisen from a horse link - it's possibly from association or confusion with hippodromes. Hippodramas exist, but are apparently dramas featuring horses.)

Label

Meaning: Originally meaning a band or strip of cloth, the meaning evolved through tatters to ribbons, on into strips of paper used to add notes or hold a seal, and then out into a multitude of figurative uses - record companies, tags on clothing, stereotypes, and even categories on blogs.

Usefulness: 2 (I've just added a labels gadget to this blog, that's how useful they are)

Logofascination: 3 (It's a word so old its etymology is murky; tag has a similar evolution - from something hanging off clothes into a way of finding things in an electronic medium.)

Triboulet

Meaning: Cotgrave:  

a slovenlie fellow, one that usually weares his hose ungartered, and shooes untyed; also, the name of a famous foole belonging to King Francis the first; and thence, any fop, cokes, ridiculous ninniehammer, or laughing-stocke.

Triboulet was indeed a fool to Francis I, not to mention Louis XII. As well as this derogatory French term, he was apparently an inspiration for Rigoletto .

Usefulness: 1 (of myself, mainly, although technically I think that would make me a triboulette)

Logofascination: 2 (I admit to cheating here, and picking up a French word rarely used in English - wiktionary lists it, but not the OED.)

Gyromancy

Meaning: much as I'd like it to mean spinning around until you fall over (which is what Rabelais appears to suggest), serious divination by this method apparently involves walking around a circle of letters... until you fall over. Or, more boringly, spinning a coin until it falls over. Cotgrave hedges his bets with 'divination by circles', which could apply to any number of things.

Usefulness: 1 (Could be applied to games of spin-the-bottle, but I'm going to talk to our safety person about how we can implement this at work; it'd be much more fun that tossing a coin. )

Logofascination: 3 (the concept is interesting, the word less so, and you're probably still digesting all that cheesecake from yesterday.)