Blogs on subdomains
 

I have domain what if put 10 blog each on subdomain no interlink at all. Is make different in SERP? I would think not, look at free blog hosts for example, so why spend money buy 10 domain.

i bump now

basically, it would work, it would be a little bit harder to get hard links on those blogs, your main domain, should get trusted rank, etc.. there are a lot of SEO tactics that you could do ... but about that some other time ;)