I have registered a lot of domains and I really have went back and forth in the past about how I should handle the parked domain if I am not ready to develop the website. I have heard many different things you should do including: Use a blank index page, put up links, leave it alone and just let the default page stay until you are ready to launch.
Well, according to Matt Cutts with Google Search. You should write a couple paragraphs about the website you are building and what it will be about. This will keep google from labeling your site parked. If your site is labeled as parked, it will take google awhile to see your site is launched and to index it with your new content. Take a look at the video, Matt can explain it better.