Just in case this isn't ubiquitous knowledge yet: please think twice before you delete (or rename, which amount to the same thing usually) your blog. There are situations where it is necessary, as with the blog I visited earlier today, however you must be prepared for the fact that spammers will move in on your old URL like the clappers, and visitors will see a page saying "I moved my blog to other domain. Let me redirect you... ;-)" before being forwarded to a site selling car insurance.
Read this for more info.
No idea how much this affects other blog hosts (I should imagine that hosts that charge money, such as typepad, are much less vulnerable), but it is definitely a problem for blogspot blogs, such as the one I mentioned above.