It’s my experience and I am sure no other expert domainer will disagree at this point. I have been developing some of domains for several years and have been parking as well. Just make sure of one thing as I am talking here about mini sites vs parking your domains. If you have the purpose of selling the domain by developing a mini website and waiting for the offers to come in than you are on wrong path.
There will be marginal chances of receiving any inquiries for the purchase of your domain. I suggest you to create a landing page of your own or park your domains where it’s clearly mentioned the domain is for sale. This increases the chance of receiving inquiries. I will give you an example of one domain which I have developed for quite some time OTAL.com. If I remember correctly I have not received an inquiry in the whole 2012. Whereas I have some low quality LLLL.com domains compare to OTAL.com and have been receiving frequent inquiries.
One of the reason behind the developed website is the potential buyer of that domain might think the project already exists and surely the current owner won’t sell his profitable company. I know many of you disagree because developed websites do sell but here I am talking the type of buyers who are not interested in buying only domain and not willing to pay anything extra for the existing project. There can be several reasons for that. One of them is the potential buyer is not willing to continue the project you have developed and have different plans and ideas for that domain.
So to conclude the post I would once again suggest you guys to create your own landing page for the domain or park at some good companies like InternetTraffic.com, Voodoo.com, Bodis.com to get more exposure in order to sell your domain names.
Feel free to shoot any comments. No matter how good or bad they are 😉