Evolving English

It's moments like this one needs a Tardis. Keen to see Evolving English: One Language Many Voices at the British Library - an exhibition that traces the social, cultural and historical influences on the English language in an interactive, hands-on, 21st century-cool kind of way. 
So if one happened to be in London right now, one could pop along and check out 'the roots of Old English, slang dictionaries, medieval manuscripts, ads and newspapers from around the world, everyday texts and dialect sound recordings' from all over the place.
It also has an audience-participation section where people can record themselves reading the kid's book Mr Tickle - the text of which apparently evokes a wide range of sounds present in the English language - the idea being that as people participate the exhibition experts compile a living 'voice map' of where we English speakers of the world are today and what we sound like. Go on, record your voice here.
This one, however, happens to be in Sydney right now. So instead I got my word-geek fix at the Gleebooks summer sale. Picked up a copy of Ad Infinitum: A Biography of Latin by Nicholas Ostler and it's bursting with stuff-one-needs-to-know.
Stuff that makes perfect sense in this Y, Z, Whatever Gen world we live in, where kids write essays on iPhones using animated emoticons, words of one syllable or less, no vowels. And some of them have never in their life felt the dewiness of grey finger-printy digits smudging the tablecloth after an hour with a real, hard copy, freshly minted newspaper. 
Stuff like this, from the cluey old Greek dude Horace - who may or may not have realised the weight of his words way back in 70BC - when he wrote: 
'Many words that have fallen will be reborn, and many that are now in honour will fall, if usage wills it, for that holds the judgement, the law, and the standard of speaking.'
I, for one, believe a Renaissance is due for the word 'behoove'. It would behoove us all to remember our words and use them wisely so that our language may flourish.
Which words do you think deserve a newfound appreciation?