Besides job boards, linkedin, career builder and monster, what are some alternative sources of employment opportunities not often thought about and how can they be useful in a job search

I personally have never used a job website to find employment. I go to friends, local businesses, community centers, even public bulletin boards for job spaces that need filled. The newspaper may be a good place to look for employment, those types of employers tend to want the space filled as soon as possible and it may lead to a better chance in getting hired. 

I wish you well in you job search.