StartUp Lifecycle Waterfall

Where there's muck, there's brass from Joel on Software by Joel Spolsky (Thanks for the link Kalpesh)

.. the great thing is that as you solve each additional gnarly problem, your business and market grows substantially.

You start out with good design, then you add some good features and triple your customer base by solving lots of problems, and then you do some marketing and triple your customer base again because now lots of people learn about your solution to their pain, and then you hire sales people and triple your customer base yet again because now the people who know about your solution are reminded to actually buy it, and then you add more features to solve more problems for even more people, and eventually you actually have a chance to reach enough people with your software to make the world a better place.