Update: The answers have been posted, mostly as the correct versions of the stamps (if such exists). Some further information on the less obvious answers is up here.
Original message: Well, it's not actually a meme as such, because I have no hope of it actually catching on... particularly because it's taken me about two years to do the research of which this is a minor by-product (and of which there is still no end in sight); but I thought I might annoy people with a guessing game.
It's simple. Behind the cut are enlarged images of ten stamps. Each of these stamps has at least one design error. None of the design errors are philatelic in nature - they'll all be obvious to an average person who knows the area shown on the stamp, and a couple of them are instantly recognisable as wrong by just about anyone.
So, if anyone is interested, have a go at guessing what the errors are. I've set comments to screened to give everyone a fair go, and will leave them screened for a week or so.
That's actually the company logo... these are all stamps issued by a private company which has an "access agreement" with the Post Office. Part of all such "access agreements" is a requirement that stamps printed by these private companies must show their company logo.