Seth Godin tells a story about Customink.com

I sent in a t-shirt order to customink a few weeks ago.
Three days later, I got a note from someone named Lori that said,

"Hi Seth,
I noticed that you have designed shirts that appear to be for a charity event. If that’s the case, CustomInk would love to make a small donation to your team or to the charity itself on your behalf.
Please let me know if your order is for one of these events. If you would like us to pitch in and support your cause, please include information about your charity event, a link if you have one or the organization’s name if there is no link to a team web page."

That's it. No policy, no standard operating procedure, no promise in advance. Just plain generosity.
It turns out that customink does this as a matter of course, regardless of whether the customer has a blog or not. They don't do it as an inducement, they just do it.
Formula: The value of a perk is inversely related to the expectation of that perk.

its all we are looking for Seth, to act like "this firm is just working for me!" ;
such proud...
such honor...
such satisfaction...
and at last,such an addictness would it be to that firm...