At the very practical end of the spectrum Nicola Andler has published a handy book of tools and techniques useful to consultants, available in kindle. Its major selling point for me is that it goes through why, when and how you might use different tools; it also cross references within the book, and has summary tables of all different kinds so you can find what you want.
You can find similar information at 12manage.com where just about every management theory, tool and idea, from Marketing to Strategy, to Human Resources has been summarised (in several languages) in just one page.
And of course my site also has free tools for running your business (invoices, time sheets, rate calculator, sample terms and conditions, that kind of thing!) which are less strategic and more practical. So knock yourself out!
