Absconded - whoa, I've already forgotten what this word means
Brackish - now normally I don't much care for any word ending in 'ish', but I'm making an exception, for this word.
Curmudgeon I have no idea what this word means, but here it is.
Cuticle as in Ode to A Pair of Cuticle Scissors
Effete, a word whose meaning escapes me.
Inflicted as used in Citizen Kane
Modicum
Miscreant
Penchant
Plonk meaning cheap or inferior wine, but it can be used more broadly.
Ponderous as in 'If you get too large, you won't be able to hunt down prey because you'll simply be too ponderous.'
Scatological - what exactly does this mean anyway? I can never remember.
Smattering is a word that can only be use successfully with a British accent.
Spate
Spry, which was first brought to my attention by a one Bernard Lischer.
Suet as in, if things don't go your way, just suet
Sully as in Jar Jar Binks has sullied my existence
Surfeit
Unction
Extreme Unction

Pretty Good Words Which Aren't Used Enough

Abominable
Inane

You're really cool if you can use these words in conversation

Averse
Avert (Avert your eyes! No, you avert your eyes, bitch!)
Inaugurate
Thusly
Requisition (but only when used during peace time)
Usurper (note: not usurp v., which would be not that hard to use, but usurper, n.)

Words not even in Microsoft's Spell Checker

Ambsace - something worthless or unlucky
Noisette - small piece of lean meat
Noetic - of, relating to, or based on the intellect

Words that are just friggin' hard to spell

Privilege (one of the most difficult to spell of all conventional words)
Burgoisie Bourgoies Bourg Bourgoisie — oh wait, fuck - Bourgeoisie
Sarsaparilla (how did they ever come up with this?)
Debuted (Debuted, Iowa? Earth to English: We don't have a silent 't'.)
Appellate God damn this word is hard to spell.
Crevasse

Words that should never be used ever in any context by anyone

Careen
Preggers

Words I saw in books which I had to look up

Opprobrium

Words with double pump rhymes (a.k.a. miraculous words)

grandmama
brouhaha

And finally

flotilla