Welcome to the Q&A Forum

To get the most out of them SEO wise, my recommendation is to develop them in to full blown websites.  15-20 pages of unique content related to the topic.  After developing these "micro" sites, they will bring in a lot of traffic not on for the exact keyword, but long tail as well. I know this sounds like a lot of work, especially if your main site is not very big, but this is how you're going to get "the most" out of them.