Examples include free trial versions, free samples, free white papers and social contests (formerly dominated by like & win promotions).
On demand subscription services are especially known for their free trial offers.
Free samples in fact ‘work the same’. By having the customer commited to a small step – ordering a free sample – she or he is inclined to take the next step sooner.
A less effective but other well known way is to offer free white papers. You and your brand can claim authority while readers are inclined to make contact with you sooner. A disadvantage here is that most white papers nowadays look like advertising brochures and are foremost aiming to obtain your name and email address for further contact.