Namecoin in itself is a peer-to-peer DNS system based off of the Bitcoin code. You use Namecoins to register your own domain, though at the moment you need a custom DNS server in order to resolve those .bit domains. Useful for the same reason Bitcoin's decentralization is useful, namely, that these domains can't be blocked by a governmental authority. The project is still in its infancy right now though.
Bitparking I have no idea.
You will always need a DNS server to resolve an host, i miss the point in this. The custom DNS can be easily blocked and i don't think anyone will fell the need of installing a program just to resolve some .biz domains.
The "untraceable" nature of bitcoins is lost in this project: IP addresses are associated to a company/person and they can be very easily blocked.
It's a nice concept, but i can't see anything more than that.
qed, you're completely missing the point of this project...I suspect by lack of understanding of the current way DNS works. This isn't the thread to discuss it, please check out
http://en.wikipedia.org/wiki/Domain_Name_System and also the main dot-bit project site
http://dot-bit.org/Main_Page . If you have further questions, please direct them to the #namecoin channel in IRC.