It's a good question.

Its really because on the back of my mind I was wondering if there's a way to have revenue without intrusive advertising or anything.

And, inspired by the games industry where people seem very willing to buy digital good to make their characters look good, I thought well thre are people on the internet who really value having exactly the username they want. And then I thought well maybe I should hold off giving away what might be a practical, non intrusive way to generate revenue. Thus I though, well the easy way is just to put a number on the end of the username. That's the thinking. If you've signed up, as an early joiner I'd be happy to give you your username without the number - email me at developers@crowdwave.com and I'll fix you up.