Great thread guys, but if you're going to do a top 10 I reckon you have at least 2 categories here. Those Spitfire ads (believe it or not) actually were used - my ex-local pub in handcross had the full complement of beer coasters as well as posters above the bar (I've even seen one or two t-shirts floating around). This was around 2 years ago, and my favourite (not pictured above) is the one of Winston Churchill doing his V sign as if ordering 2 pints. Dead right btw, it is lovely beer!
So you have 2, maybe 3 categories for top tens:
Ads they dare not run
Ads they should not run, but did,
and maybe Ads that have 'improved' by a bored/disgruntled third party...