Not to be confused with my own CareerStorm Navigator, this is is a site dedicated to setting up your own business; Venture Navigator.
Venture Navigator was created by the Business Edge Consortium which cosists of the Universities of Essex, Cambridge, Leeds, Liverpool, Glasgow and Warwick plus The Open University.
In particular, I like the following (free) assessments:
Five forces assessment.
General business viability.
Business Tools and Techniques.
There's also a groovy online community where you can ask questions and have clever people answer.