Can you show me a mock-up to help us choose a designer/developer? No.
I fell for this once when I was young and naive. I made no money and wasted lots of time. Don’t do unpaid work for the chance to be paid.
This wouldn’t fly in any other industry, so why web design? The best case scenario (though rare) is that you get a job with a client who knows that you’ll work for free when necessary. The worst case scenario is that they don’t pay you, and still use your stuff, knowing you don’t have the legal resources to do anything about it. Most likely though, you’ll just waste time.
Quoted in CreativeBits by Ivan Raszi.