Where did many CEOs of the fastest-growing companies get their ideas for new products and services? From -- you guessed it -- the It Just Came to Me Department. Formal research and development, it seems, rarely fueled diversification.

Just saw market niche 46%

Formal R&D or product- 20

development process

Customers 17

Acquired another company 3

Other 32

Source: An Inc. survey of 463 private companies reporting a five-year growth rate of 713% or higher since 1985.

Note: Total is higher than 100% because of multiple answers.