Over time I have turned into a fan of Fred Wilson from Union Square Ventures, relatively famous for investing in Twitter or Foursquare. I like VCs who know what they are talking about. Watch this video, it contains more wisdom on product design than many talks by product guys. Wilson’s 10 principles are:

1. Speed

2. Instant utility

3. Personality

4. Less is more

5. Programmable

6. Personal

7. Restful (meaning anything should have a URL)

8. Discoverable (i.e. SEO)

9. Clean (one could see this as a duplication of 4)

10. Playful

It is also worth listing to the Q & A in the end: The product has to be the marketing vehicle for the product itself.

The 10 Golden Principles of Successful Web Apps from Carsonified on Vimeo.