This is from the January, 2009 Identity Marketing journal:  In the summer and fall of 2008, the Advertising Specialty Institute conducted a survey of 618 business/professional people in New York, Chicago, Los Angeles and Philadelphia to understand how promotional products influence end-users purchasing decisions.  Writing instruments are the most recalled items (54% of respondents recall owning imprinted ones), followed by shirts, caps and bags.  42% of respondents indicated that their impression of the advertiser had become either significantly or somewhat more favorable after receiving the item.  62% of respondents indicated that they had done business with the advertiser after receiving the item.  This is quantifiable evidence that promotional products drive business to your clients!