Ask any SEO professional how a domain affects your search engine ranking and you'll probably get a few different answers. The importance of how a domain name influences your ranking has changed a lot in the past few years, so those SEO guys were probably correct in their thinking at some point in time.
Here's an update on the impact of Parked Pages on how Google indexes your domain name. This is updated information according to what Google published as of November 2012.
First I need to explain what a Parked Page is. When you first buy a domain name from a Registrar like GoDaddy, Network Solutions, Enom, Register.com, or any other company the domain will immediately appear online so you can see it. Regulations stipulate that you must have your domain listed in the world wide website directory service through the Domain Name System, commonly called DNS.
The DNS is the magical service that translates your domain name into computer numbers. Computers do not understand humanly readable domain names, they only understand numbers. This is akin to the contact list in your cell phone. If you wanted to look up my phone number in your contact list you would look for Matthew Perosi (a humanly readable name) instead of my phone number.
Several years ago, when you bought a domain name you would immediately need to pay a hosting company so they could list your domain name in their DNS, and put a coming soon page up for you. This was a very frustrating process, especially if you were buying dozens of domain names since that meant you were also paying for dozens of hosting services. This got very expensive and it would dissuade people from buying multiple domain names.
In an effort to increase their sales, all the Registrars started offering "Parked Page Services" that would immediately set up the DNS for you and create a generic parked page for you. The parked page usually has AdWords ads and a random image. For a while this parked page was a huge boon and an aide for brand new domain names because Google would find those new domains and index them.
Prior to parked pages, when you launched a website you also needed to immediately launch some type of link building strategy. Google crawls the web through links, so without a link to your website you would be a lone island site and no one would ever find you. The parked pages gave Google something to read an index. Google also put the parked page on their queue to revisit often in search for new content; therefore Google would find your new website within hours after it was eventually launched.
New website owners usually don't know how this all worked, and they were amazed how quickly Google found their brand new website.
Now that you understand the background I'm here to tell you that regretfully, it's all over now. Google now has the ability to detect all of those parked pages offered by the Registrars and they put them on a slow revisit schedule. So if you do use a parked page for your domain you will find it takes days, or even weeks for Google to eventually switch you from the slow revisit schedule to the normal revisit schedule.
What I'm describing here would be a detriment to e-commerce sites because those sites need to start making money from the first day they are launched. It might not be so important for small business informational websites.
In conclusion, this topic plays an important role in the launch of new websites. Once you buy your domain name you will need to immediately set up a hosting account and put your own "Coming Soon Page," rather than one of the generic parked pages offered by the Registrar. The coming soon page should have a few sentences to describe the new site, nothing fancy.
Oh, and one last comment, once you've created your coming soon page you should share that page through Twitter, Facebook, and Google+ to insure that the search engines find and include you in the normal revisit schedule.