Alas these are mostly neologisms created by combining roots from classical languages. That's a recipe for creating new "obscure" words pretty much on demand. The best sort of obscure words are ones that are obscure because they're old or highly specialized, not because someone made them up and they never really became part of the spoken language.
Extraordinarily, the Slavic languages are chock full of calques that originated in just this way. Educated Slavs in the 17th-18th centuries deliberately modernized their own languages by taking Western words, translating the morphemes individually, and grafting them back together. Modern Czech in particular, if I remember correctly, was largely constructed in this way. The classic example is German Zeitschrift (magazine) being translated zeit → čas (time) and schrift → pis (writing) to produce časopis, "timewriting". Russian has tons of words like this from French (traduire, to translate, went tra → пере (across) and duire → водить (lead) to become переводить, "to crosslead").
Normally such concocted species (like the neologisms in the OP) fail to take root and soon wither. The difference here is that these words were badly needed in daily life.
This list is a clear illustration of why it's better to read Infinite Jest on the iPad book reader, where dictionary definitions are a tap away, than in dead-tree format. Because I'm only 2/3 through and I can't guarantee that he hasn't found a way to use the word "exergue" in a non-coin-related sentence. Probably in a footnote. Which, by the way, is hyperlinked in the iBooks version.
Unrelated: What is the point in publishing an interesting list such as this and then restricting my ability to highlight so I can copy and paste? (Chrome 4.1 on Windows)
What's the point in choosing a tool which doesn't give you the power to do what you want, then coming on the internet bitching about it?
Your browser is doing the restricting. If you can't override that then it's not working in your interest, it's working against you on the web publisher's behalf. Dump it.
This reminds me of that board game (I forget the name) in which some silly definition is read and the players have to make up words and convince their opponents (who are guessing which word matches the definition) that their word is correct. With some of these words, I feel like I'm playing that game and someone is trying to trick me. I mean, zenzizenzizenzic is a number raised to the eighth power? Seriously? But it exists! http://en.wikipedia.org/wiki/Zenzizenzizenzic
Next time I need a put-down for someone's argument, I think I might call it "jumentous," which according to this page means "[s]melling like horse urine."
