Flickr won my online photo management business almost exclusively through their copyrighting. Stuff like this:
At the very bottom of their "about" page: The fact that you've read to the end of this entire document and are hanging out at the bottom of this page with nothing but this silly text to keep you company is proof of a deep and abiding interest on your part. What are you waiting for? [call to action appropriately placed here]
On their "create an account" page: Our hatred for spam is difficult to articulate.
On their "press" page: You suspected all along that our "Aw shucks" Canadian modesty was a big charade, and by George you were right!
From their company blog announcing acquisition by Yahoo!: Woohoo! What does this mean? It means that we'll no longer have to draw straws to see who gets paid, schedule conjugal visits between trips to the colo....wait! That's not what you want to know. This is what you want to know ...
And Flickr cultivates our relationship through personality-rich communications like this one:
The Flickr team has up and moved this week to Californ-i-a and has been singing Beach Boys songs non-stop since arrival. And you're moving too! ... every pixel, bit and byte ... Thank you, Flickreebies, for making Flickr such a wonderful place to share, connect, and befriend. We love you! (In an entirely non-creepyway.) - The Flickroobies
Remember, online you're talking to your audience one person at a time. Of course Flickr's personality won't work for everyone. The point isn't that you need Flickr's personality. But a personality - something to distinguish you from the crowd - would be an idea.