It says here in an advertisement by Nescafé that shoppers who buy a hot beverage in store are more likely to buy into other categories and spend more than other shoppers. The figures Nestlé quotes are that they will buy 4.8 items per trip (versus 2.8) and spend £10.47 versus £5.10.

Surely it must be worth taking five minutes out and doing the sums for your shop. (Pity the Nescafé ad is silent on the margin potential!)