Paul Buchheit on The most important thing to understand about new products and startups:
For web based products at least, there’s another very powerful technique: release early and iterate. The sooner you can start testing your ideas, the sooner you can start fixing them.
I wrote the first version of Gmail in one day. It was not very impressive. All I did was stuff my own email into the Google Groups (Usenet) indexing engine. I sent it out to a few people for feedback, and they said that it was somewhat useful, but it would be better if it searched over their email instead of mine. That was version two. After I released that people started wanting the ability to respond to email as well. That was version three. That process went on for a couple of years inside of Google before we released to the world.