Administrative

Business and Office Skills

MindTools - Offers free content on a variety of business tools.  If you create an account; you can customize a learning plan. 
Businessballs - Free online team-building and motivational training resource established and run by the Alan Chapman Consultancy of Leicester, England. Offers free templates, ideas, and thoughts.  
 

Writing and Language Skills

Merriam-Webster - Online dictionary and thesaurus
Word of the Day - Free daily vocabulary word
Purdue Online Writing Lab - Free writing resources and instructional material
Business Writing Tips - The Write Stuff: A Style Manual for Effective Business Writing, by Richard Anderson and Helene Hinis, is a great resource for tips and rules.This 93-page PDF is a great desk reference.
 

Miscellanous

CEO Express - News, travel, links, tools & more for executives.
GreaterGood.Berkeley - Greater Good Science Center provides research backed tools to boost happiness, resilience, and kindness. Topics address perspective, stress management, and appreciativeness.  
Grant Writing Tips - How to's for Grant Writing