Mechanics vs. intent
There are a thousand things you can do to improve the mechanics of people spreading the word about you, your conference, your product, your event, your service. You can create hashtags, provide kiosks, host discussions, give out free postcards or hand out bumper stickers. There are plenty of useful tactics available to you.
Mechanics are important, no doubt.
More important by far is creating a desire to share. If people intend to share, they'll find a way, the mechanics are just a convenience. But if you don't go the extra mile and I end up not caring, all the tactics in the world won't help.