Because you never know when someone is going to show it to a friend.
Give away samples, handouts, shirts, stickers, toys–everything. Most will never be seen again, but every so often you get a big score.
I sent 300 copies of my word of mouth marketing book to the BazaarVoice Customer Summit. One of them showed up on Ze Frank’s show on Time.com.
(Watch Ze — he’s one of the smartest and funniest people I know. I talk with Ze here about why viral marketing is a myth.)