OK just to kick off (and forgive me if I spell them wrong, it's always a gamble with these buggers)
Words I constantly misspell:
Mispell
Successful
Tommorrow
Concientius
guarantee
and a word I can never remember the correct meaning of:
Opaque (Can never remember if it means transparent, semi transparent, milky, partially milky and partially clear as crystal, totally untransparent ....aaaargh what is it!)
Also as a footnote.
What is the difference between flammable and Inflammable
Opaque is a word that always seems to have the opposite meaning to what it should have - to my mind anyway.
I never know what that means either, which makes buying tights difficult. 
diarrhoea/diarrhea
I was pretty good at remembering the US spelling when I was over there, but now I can't remember how to spell either.
Quote: Dkmj @ October 19 2009, 8:18 PM BSTWhat is the difference between flammable and Inflammable
I don't think there is a difference.
Quote: Dkmj @ October 19 2009, 8:18 PM BSTAlso as a footnote.
What is the difference between flammable and Inflammable
The word "inflammable" came from Latin "'inflammāre" = "to set fire to," where the prefix "'in-"' means "in" as in "inside", rather than "not" as in "invisible" and "ineligible". Nonetheless, "inflammable" is often erroneously thought to mean "non-flammable". To avoid this safety hazard, "flammable," despite not being the proper Latin-derived term, is now more commonly used, not only as a warning label, but in standard speech and writing as well, when referring to physical combustibility. (Wikipedia)
Sanction always gets me. One of those rare words with two totally opposite meanings, depending on if you use it as a verb or a noun (but why??????). How words can be allowed to end up meaning two opposite things is just bizarre and shows what a twisty route the English language took. Surely one of these meanings should be kicked out. Just look how confusing and/or ridiculous it is - 'I sanctioned the use of sanctions against him.' 
Quote: Alfred J Kipper @ October 19 2009, 9:04 PM BSTSanction always gets me. One of those rare words with two totally opposite meanings, depending on if you use it as a verb or a noun (but why??????). How words can be allowed to end up meaning two opposite things is just bizarre and shows what a twisty route the English language took. Surely one of these meanings should be kicked out. Just look how confusing/and or ridiculous it is - 'I sanctioned the use of her using sanctions against him.'
Isn't it just the same as "enjoin" or "warrant"?
I don't know about the spelling, but I always have great difficulty saying chassis.
neccessary ... maybe I resent the meaning
weird or is it wierd? That's what I never remember
Bizarre and bizzare.
I belieeeeve it's the former...
?
I always look it up usually, but I won't this time.
Bizarre is one of my favourite words. I use it as often as I can.
No, warrant has different meanings but so do thousands of English words. There are very very few that have two meanings, both of which are opposites. It really is bizarre just why or how this has been allowed to happen.
Quote: Nil Putters @ October 19 2009, 9:08 PM BSTI don't know about the spelling, but I always have great difficulty saying chassis.
For my final-year group uni project, I was responsible for designing a lightweight vehicle chassis - In the first meeting where we split the project roles, I had to learn how to pronounce it >_<
It's a bugger alright.
Quote: Alfred J Kipper @ October 19 2009, 9:17 PM BSTNo, warrant has different meanings but so do thousands of English words. There are very very few that have two meanings, both of which are opposites.
"I'll warrant the use of a warrant"?
Isn't that the same as your sanction example?