Expanding your basic knowledge of key concepts in business doesn't have to break the bank. In fact, many reputable institutions and companies offer free online business courses that can help professionals in many ways, including achieving proficiency in software and gaining leadership skills.

Here are some online classes for professionals to check out:

People and Organizations
MIT OpenCourseWare
This self-driven course provides lecture notes on important business concepts such as teams and teamwork, contemporary management challenges, and negotiations.

How to Write a Business Plan
Trump University
Get a refresher in how to write a business plan in this short course. This class is accredited by the International Association for Continuing Education and Training.

Technology 101: A Small Business Guide
U.S. Small Business Administration: Small Business Training Network
This free small business course provides an overview of how computers, technology, and the Internet are being used to help launch small businesses.

Entrepreneurial Behavior
The Open University
Get an overview of what's involved in becoming an entrepreneur in this free, 20-hour class. Areas of study include entrepreneurial qualities and entrepreneurial work style.

Introductory Economics
Carnegie Mellon's Open Learning Initiative
Review the principles of supply and demand and other economic basics with online experiments and related workbooks that allow you to put these concepts to practice.

Improve Your Personal Networking Skills
Hewlitt Packard Learning Center
Take this class and develop proven interpersonal skills to "woo and wow potential prospects." HP also offers other general courses on topics such as software proficiency.