There are people that have trouble summarizing things: business plans, arguments, feelings, etc. -- I suggest that they try haiku. Haiku requires that you follow a strict structure that consists of the following:
Don't misunderstand my intention: I'm not trying to make you sound like Confucious by strictly adhering to the rules, rather it is the process of distillation that can make for strong summaries (putting a haiku at the top of an executive summary might not earn you too many points, while sending someone you love a haiku might earn you big points).
Are hardest to create
I like to use whiteboards to write down haikus as they can be easily erased, changed, and modified.