Just discovered Andy Swan's blog thanks to @fredwilson - great read.
This post rang close to home:
From http://andyswan.com/post/16525016414/having-a-coreDefining your core is extremely important. The result is simple, but the process can be very hard. Sticking to it is even harder.
Your core should boil down to one sentence that defines WHO your client is and what BENEFIT you will bring to them.
It absolutely should contain no technical terms, no buzzwords.
This is the sentence that you can etch into marble today with the intention of it being placed above the entrance to your corporate HQ skyscraper 50 years from now.