Here's the list of the top 100 most often mispronounced words.
I'm feeling sensitive to it lately from getting a dose of so many accents (Californian, New England, Canadian, Albertan (ah!), South-western US), and keep picking up mistakenly pronounced words all the time.
However, I'm not perfect either, so here's my list from the top 100 that I know I mispronounce (excluding the ones I think are stupid like "champ at the bit" - what?):
barbituates should be "barbiturates"
dialate should be "dilate"
diptheria should be "diphtheria" (I had no idea actually)
'erb should be "herb" (supposedly)
jewlery should be "jewelry" (which I knew but meh)
long-lived should be "long-lived" (go look it up!)
often should be "ofen" (what???)
persnickity should be "pernickity"
silicone should be "silicon" (no, it's Silicone Valley)
supremist should be "supremacist"