This is a great article but again, like the last article posted here about your MVC setup, I'd personally like to see examples. For instance whats an example of good asynchronous code?
I'm taking a bit of time with it to make sure its actually useful to people and not just a stub. Feel free to check out what I have up there so far.
Quick side note - you might want to add simple validation for sign up form for exipe.com - it currently accepts empty string as a valid value.