Give them freebies... everyone like it...
That works to get them to optin but to stay onsite, not so much. Once they are done downloading, your lucky to get them to open an email or log into the site ever again.
Besides, you don't want to hook them on freebies forever, because then they never buy anything. You train your visitor what to do and expect from you by your interaction with them. People don't realize they are training their visitors never to become customers/clients because they are just so happy to get the traffic working in their favor.
Focus on getting them in the door with that guru style freebie offer but then, keep them there with maintaining their focus and interest. Freebies only go so far before information overload kicks in and they are so busy downloading your freebies, they don't take your offers seriously as you have turned them into a freebie download zombie at this point.
If you want to monotize the download method, have a free zone and then upsell it with the upgrade of membership on the offers. It is like GreyWolf mentioned in another post about an old episode of Frasier...Frasier and Niles found a spa pass that wasn't meant for them, sneak in and enjoy their day...UNTIL...they see the door for the next level of membership.
The spend the rest of the day sneaking in through door after door, only until the episode ends with them plotting to go through the next door. This place must have been 3 miles of building, as many levels as they went through. I remember it vividly, as their was wood paneling EVERYWHERE in the rooms.
Leverage it to your advantage with by making them curious as to what is on the other side of your membership upgrade door. The number one mistake people make with this is in showing what you get if you buy up. That kills the mystery and people walk away cold/numb to it.
Give them something that they can make use of...games entertain them while at work doing routine tasks and access to their friends through the facebook game method. The posts keep the traffic and content counts up for facebook's side of things.
There are many alternative methods but, be careful to think them out not only for getting traffic but to monotize as well.