High school diplomas seldom open doors to lucrative employment these days, and a bachelor's degree is considered a requirement for many job seekers as they plan their work lives. But there is a middle ground: the two-year associate's degree, which can lead to a surprising number of well-paid jobs with excellent long-term prospects.

Many of these types of jobs fit into the middle-skills category, and while that particular area has suffered since the Great Recession, there remains a variety of these occupations from which to choose -- if you know where to look.

Here are five high-paying occupations that are attainable after completing a two-year-degree program, generally at a community college. Median pay levels are from the Bureau of Labor Statistics and reflect wage data for the year 2010.

1. Radiation Therapists 
One of the highest-paying positions attainable with an associate's degree, radiation therapist is just one of several jobs available in the expanding health care sector. These employees generally work in hospitals or cancer clinics, operating machinery that uses radiation to treat disease. Median pay is right around $75,000 per year.

2. Nuclear Medicine Technologists 
These health care workers make more than $68,000 per year and usually work in hospitals, preparing patients for screenings and administering scans to detect disease. Some states require nuclear medicine technologists to be licensed as well.

3. Dental Hygienists 
Employees in this field take home more than $68,000 annually and work primarily in dentists' offices. Dental hygienists are often able to work flexible hours, and projected job growth is 38%, with another 68,500 jobs being created within the next few years.

4. Diagnostic Medical Sonographers
These folks use sonographic imaging equipment to conduct ultrasound procedures and usually specialize in particular areas of the body. The median pay is $64,380 annually, and this position is predicted to enjoy explosive job growth over the next few years -- 44%, according to BLS. That surpasses dental hygienists and is more than double the rate for radiation therapists and nuclear medicine technologists, both of which are expected to grow by a respectable 19% to 20% by 2020.

5. Nuclear Technicians
This job sector is growing at an average pace and, unlike the health care jobs, these positions require some on-the-job training. The annual pay is $68,000, and technicians usually work at nuclear power plants in one of two capacities. Operating technicians, for example, are focused on the performance of the nuclear facility, while radiation protection technicians are expected to monitor levels of radiation in order to protect those working at the plant -- as well as the environment outside of the facility.

Although the health care sector is a leader in the middle-skills-jobs category, there are many other areas that offer comparable positions for graduates with associate's degrees. Many states have published a listing of such jobs, often with pay scales and training requirements. For those willing to do a little digging, a two-year degree could be the beginning of a career in a position that promises excellent pay, interesting work, and the potential for future growth.