How I feel when it happens
One of the biggest issues in guerrilla web development is that "guy" with the great idea for a website. He promises it will make billions of dollars in a matter of minutes. It's the greatest thing since the invention of fire. He knows he's on to something big. And YOU, you lucky web designer/developer you, can get in on the ground floor. How's about ten percent of the profits?
No. How about my fee? Your idea might be as great as you claim, but you're asking me to work for a wager instead of a wage. If it's going to make you billions, then why won't you invest a couple of thousand now to get a cool website? If you're so brilliant, Mister Next Big Thing, then why do you need me in the first place?
Foxes and hounds, what we do matters. What we do is not a hobby -- it's a career. Never fall for this ridiculous proposal. After all, ten percent of nothing is nothing. One hundred percent of nothing is nothing. And you shouldn't work for nothing.
As for you potential clients -- this is "What Not to Do, Course 101." Designers have to eat, too, and we shouldn't have to wait a few months until your great idea makes money. Be prepared -- have a budget, be willing to negotiate, and understand that we can't pay our bills with your promises. Your money will do nicely.