Lindt: 2 dine-in drinks for the price of 1
You may need a voucher to get the deal, although today they just gave it to me without asking. At the shop they had a pile of vouchers on a table, so you could always just wander around the shop, look at what's on offer, pickup a voucher and then arrange for the drinks before sitting down.
Now their normal prices are not cheap at face value, but when you count this deal in it's excellent value. In fact, when you sit down (assuming you go the hot chocolate - I recommend the less sweet dark chocolate) you get a small cup of liquid chocolate, a pot of hot milk, and a cup. It easily makes three cups of chocolate so it turns out to be not much more than $1 a cup or so.... oh, we also got a chocolate ball on the side.
Lindt is not my absolute favourite chocolate, but it is very good quality and easily beats a standard hot chocolate that's probably made up of Nesquik dust at best....