I want that blog name

A: Is there any way to transfer the address of a defunct blog to my site?

A: Yes, there is but you will have to do all the detective work by yourself. No one else is willing or able to do it for you. Google definitely will not help you because a blog is forever:
http://www.google.com/support/blogger/bin/answer.py?answer=41931

Even if you manage to contact the owner and he agrees to delete his blog, the URL is still not available to you. You need to show him how to transfer ownership of the blog to you. It is not a simple process. Since he has not used his blog in years, he probably hasn't got a clue how to do a transfer properly, (even if he remembers his ID and password). If he doesn't, then you probably have to show him how to get back his forgotten data for signing on to his forgotten blog. It is not really worth all this effort.

A blog is popular not only because of its unique name. Quality and quantity of the posts are also very important considerations for attracting visitors. Blog name can be shared by many blogs; but blog address (URL) has to be unique. Be happy just sharing the blog name and start posting to your blog today. You can always change your blog address later when you think of a better URL.

Change a blog name

Q: How do you change a blog name?
A:  Blog name and blog address are not the same thing.

Change blog name (title)
Please go to settings>>basic>>title.
Make the changes.
Save settings

Change blog address (URL)
settings>>publishing>>Blog*Spot Address
Make changes inside the box.
Save settings

However, please be aware that changing blog address may have adversed consequences:

You may lose 

1. all your followers

2. your blog's established Google ranking

3. adsense earnings
4. feeds
5. domain connections
6. backlinks

source: http://www.google.com/support/forum/p/blogger/thread?tid=6349d53c6da7f902&hl=en&fid=6349d53c6da7f902000474c2946c31ba

change blog name

Q: How do I change my blog name?

A: Change blog name
Please go to settings>>basic>>title.
Make the changes. 
Save settings

I want someone's blog name

Q: Two accounts are dormant for over 5 years. How can they be deleted so I can use them?

A: It seems that a blog is the property of the owner forever, irrespective whether he is active or not. However you could try to contact him and then convince him, some how to transfer the URL to you. Good luck!

Deleting the URL will not make it available to you. it has to be transferred by the owner to you.
http://www.google.com/support/blogger/bin/answer.py?answer=41931
source:
http://www.google.com/support/forum/p/blogger/thread?tid=24fb5e70314dec28&hl=en&fid=24fb5e70314dec28000470c4d0741ffb

Another link explaining why not:
http://blogging.nitecruzr.net/2007/11/use-detective-work-to-find-blog-owner.html

changing blog address

Q: How do I change the name of my blog?

A: Please go to settings, publishing (change the name inside the box). Save settings