Istanbul Visa.
Anyone going that way should note that the kiosk where the little bloke swaps ten quid for a stamp can be carefully hidden behind the door you enter through depending on your arrival gate.
Those in the know enter the immigration area and promptly perform a U-turn to purchase their Visa stamp at the deserted kiosk which is usually manned by one elderly Turkish gentleman (eight or so immigration desks though, go figure). They then proceed to the now-deserted immigration desks, battling against the tide of humanity coming the other way as the lumpen proletariat get told where to go to get their stamp by the immigration officials.
How they must laugh in Istanbul and I am eternally grateful to the person who warned me about that one.