Selling domains on your own server

I've decided I want to sell my domains on my own server as I don't think its a good idea to park them with someone else. However, I need to ask you guys what is the best site layout or structure to sell them on your own. Let me explain, I want to add relevant original content to each domains page but I also want a main portfolio page that lists all available domains as well. The way I've been thinking is to build a site in my server root that lists all of my domains as a portfolio and then have each individual domain in its own directory off the root. Then i'd link every domain back to the main root site as well as cross linking to all other domains. This seems like the most logical way but I have a big concern over this method.

My domains cover a wide range of unrelated, non-relevent subjects and I'm worried that this would hurt any organic seo if there all linking to eachother. I'm concerned it would make it pointless to even bother adding any original content to each domain. What do you think?

Can you think of a better way to layout domains for sale on your own server? Or, how about if I used wordpress multisite instead and gave each domain its own little blog... would this be any better or would I still get penalized by Google for having so much non-relevant content linking to eachother?

Its a tricky one don't you think? :confused: