Rob Ryan (Of Ascend Communications fame) has written a great book that every entrepreneur must read called Smartups

The core of the book is about business models. Rob describes the business model as a sunflower. The analogies are:
a) core competency as the center of the flower,
b) various products and services branching out as petals of the flower and most important
c) assumptions on which the model is based as the stem of the flower

It’s an interesting model. If you are an owner of the business or in
way influencing where your business is going – it may be a good idea to
view this via the sunflower model and check on what assumptions the
business is based on. We know that if the stem is cut off, the flower
dies. Applying this, if the underlying assumptions are not valid, there
will be business challenges that we should be prepared to handle.

I love the sunflower model because of its simplicity which is a topic in itself (that I will post more in the next few days)