Here's one of the great things about English - since it is ruled by popular usage, all it would take for words that have long fallen into disuse to come back into fashion is for people to start using them again.
A blogger is trying to do just that, by taking a selection of 20 words from Erin McKean's series on weird words - titled Weird and Wonderful Words and giving definitions so people can start slipping them into conversation.
The words include wonderful terms like jargogle (to confuse), jollux (a fat person), ludibrious (to be an object of mockery), brannigan (a drinking spree or 'bender'), and illecebrous (alluring or attractive).
Using words like these - many of which haven't been uttered in centuries - would confuse the people around you, but who knows... maybe one of them will take off. The internet has certainly proven itself to be a great tool in coining neologisms and spreading them around the world!