Almost every web hosting provider provide the domain selling too. It is a “side business” for them, and in some case it helps their customers to setting up their website/blog easier.
But, for me, buying a domain and a hosting package from the same seller is not a good idea, especially if we manage a lot of domains. I prefer to buy domains from the well-established domain specialized seller : godaddy (godaddy.com) and name (name.com).
