Some of the most interesting things happening in online learning are taking place not in the realm of individual online classes or online degrees, but in the space between the two.

Members of certain professions, such as IT, have long participated in online certification programs comprised of individual courses or sets of courses, with the passing of high-stakes exams (such as CompTIA’s A+) the prime marker of success — as well as a ticket to a higher-paying job.

The territory between courses and degrees also includes ongoing professional-development programs in fields like education and accounting, where professionals must participate in ongoing training to receive and maintain certification. And, as with other formal but non-degree bearing learning, professional development credit programs are increasingly moving online.

The availability of paying customers in this segment of the market has led to a number of new programs with innovative business models emerging in fields where something short of a full degree has demonstrated market value.

Harvard University — an institution that has made huge investments in free online learning through their commitment to the edX Massive Open Online Course (MOOC) consortium — has also been at the forefront of paid, certificate-based non-degree education.

For example, the Harvard Extension School, which allows students to take individual courses or earn an undergraduate or graduate degree, also offers a series of Professional Graduate Certificates in areas such as Business Communications, Natural Resource Management and Sustainable Ecosystems, Data Science, and Museum Studies. Earning an Extension School certificate involves taking 3-5 courses in the specific area of study, with most Extension School courses offered on the Harvard’s campus at a price of approximately $2500 per course.

On the online front, Harvard Business School (HBS) recently introduced HBX, an initiative that provides students access to core business school online courses without being enrolled at HBS or any other MBA program.

Unlike the comprehensive training one would receive as an MBA student, HBX focuses on a subset of skills relevant to anyone working in a business environment. Their initial HBX Core offering includes three online courses covering Business Analytics, Economics for Managers, and Financial Accounting. And their target audience includes undergraduates who might want to build business skills without majoring in the subject, or college graduates who find themselves in a business career that requires understanding of accounting and economics, but not necessarily an MBA.

Another field where the need for knowledge transcends a traditional profession is law, given that executives, managers, and many others are increasingly involved in transactions and interactions where an understanding of contract law or other legal matters is vital. And even practicing lawyers need to keep up with their field, which they can do through an increasing number of courses (both live and online) that — like HBX — focus on specific subjects such as contract and criminal law.

While Massive Open Online Courses have been synonymous with free learning, one of the biggest MOOC players, Coursera, recently introduced a new Specialization program that allows students to combine multiple courses into something that’s not a degree, but represents more than a bunch of unrelated classes.

Coursera has been offering both paid and free versions of its classes for years. While both are identical in terms of content, paying for a Coursera MOOC via the company’s Signature Track program adds a level of security that attempts to ensure students are doing their own work. And those who complete a course under the program receive a special Signature Track certificate that seems to be developing caché in the marketplace (the organization had sold over four-million dollars’ worth of Signature Track certificates at the start of 2014).

Specializations take this process one step further by stringing together a set of courses (all taken under the Signature Track umbrella) and requiring students to complete a capstone project that integrates material from all those courses together. The company already has over two-dozen Specialization offerings in areas such as Data Mining (offered by the University of Illinois at Urbana), Interactive Design (the University of California at San Diego), and Reasoning, Data Analysis and Writing (Duke University) with the total cost for completing a Specialization under $1000.

At a conference on online learning at MIT last year, Sir John Daniel, former President of the UK’s Open University (the largest distance educator in the world), criticized MOOCs for not providing an option to receive a formal degree — still the coin of the realm in terms of turning education into opportunity. But with the emergence of new certificate programs like those described above, it’s an open question whether something more than a course but less than a degree might become a new and accepted unit of learning, one with a price tag people will willingly pay for the benefit it confers.