When applicable, try and utilize promotional merchandise that can measure ROI (return on investment). By requiring your target audience to do something in order to get something, you can effectively measure the success of your promotion. Here is an example:
With competition for employees at an all-time high, Cosi, a convenience restaurant with locations in more than 15 states, was looking for a way to drive job hunters its way and build a database of interested applicants. The solution? A music download promotion tied to a customized online registration page.