My go to site for quizzes, assessments and resources for personal and professional development is MindTools.com.

This site has 1000+ pages of resources conveniently divided into an array of categories:

Access the main page here: MindTools.

From their “The Toolkit” Page

Use links below, in the menu on the left or on the Toolkit menu above to access the Mind Tools toolkit.

Leadership Tools
Whether you’re in a leadership position now, or you’re working towards this, you can become an exceptional leader!

Team Tools
Learn the full range of skills you need to manage a team successfully.

Strategy Tools
We’ll show you the strategy tools taught on MBA courses, and how you can apply them to your situation right now.

Problem Solving Techniques
Devise better solutions to the problems you face by using the skills set out in these articles.

Decision Making Tools
Add some rigor to your decision making with these tried-and-tested approaches and processes.

Project Management Skills
Find out about the formal disciples of project and program management and change management.

Time Management Tools
Beat work overload, increase your effectiveness, and achieve more.

Stress Management Techniques
Learn a range of techniques with our holistic approach to reducing stress.

Communication Skills
From listening to writing emails, running meetings and giving presentations, these tools are vital to your career success!

Creativity Techniques
Learn some powerful and reliable ways of generating the fresh, new ideas you need.

Learning Skills
These articles help you handle information better, learn more effectively and remember things better.

Career Skills
Don’t leave your career progression to chance! Find out how to develop the career you want.

They also have memberships for individuals, organizations and businesses to use in their HR / People Development strategies. Find out more here: MindTools Corporate.If you know of other great sights, or have observations/critiques on this one, I’d love to hear your thoughts.