There are many very clever examples of companies using promotional products to their advantage this way and giving them away free.

A shop called 'CEX' for example specialises in buying and selling electronic items and DVDs etc. When they sell an item however, they also give away promotional bags, and not the usual bags that you get, but good quality drawstring bags. Drawstring bags then mean that the bags are far more practical and people are likely to be a) very pleasantly surprised at the free item, and b) very likely to use it as they go about their business. This way then people are giving CEX free advertising.

Similarly the bank Barclays is equally as clever in giving away free promotional pens to customers. These are in a box with an invitation to keep the pens written on it – so that people sign the cheques etc and then pocket their promotional pens afterwards. Again this then means that those people will use the promotional pens outside of the bank and these will be seen by many people as a result.