Why word of mouth doesn't happen
sethgodin.typepad.com
sethgodin.typepad.com
You are gaining something, indirectly, even if you don't realise it - more users for Pandora, for example, means they are less likely to go out of business. Also, it may not mean anything to you, but there's a certain cachet in being the one in your social circle who recommends 'cool' new products.
Most people are flattered to be asked for advice, and would like to think that their recommendations show what good taste they have.
I am a strong believer that everything we as human beings do, no matter how "selfless" it seems, is always done because it benefits us in some way. These two indirect methods are good examples of that and I'd be the last person in the world to say I do anything "just to be nice."
This is the basis of the entire MLM industry. There are many other good examples, too. (Refer 10 friends, get a discount.) Not everyone likes it, but it works.
For example: I joined PayPal 10 years ago because my friend coaxed me into it. PayPal paid me $5 for joining and paid my friend $5 for inviting me. We invited lots of people..
On the other hand, consider GMail. It was just so massively superior to anything else out there that as soon as I heard about it I was hooked. GMail was (and is) free, but back then people were actually paying for invites..
Anyway, I doubt anybody really thinks about this before coaxing their friends, but broadly speaking "so do I" holds true.