Finding abandoned blogs - This is an old technique and I think it's worn out and won't work any more...But I'll post it as it may create some ideas. It may work for some of the social networks, etc.

The goal is to find third party pages, blogs and profiles that have PR and see you you can't take control of them.

1. Visit a blog host or social network provider

2. Figure out the syntax they use for their URLs...Is it a subdomain?

3. Create a "404 error" by typing in a URL that obviously doesn't exist, using a "username" that doesn't likely exist. Refer to #2 to figure out where the User name is located in the URL.

4. Go to google and do a Search in this format;
intitle:somethingfromtitle site:bloghost.com "text copied
from error page"

5. Look to see if any old blogs or other resources now displaya 404 error or deleted message and are still indexed by google

6. Go back to the free resource host and see if you can create an account with that user name.

Assuming you can find some accounts that work, you may be able to pick up resources that already have PR and inbound links, and is already indexed in Google.

If everything works well and the blog provider frees usernames after
the account is deleted, you should be able to register a blog that
already has pagerank, backlinks and has already been indexed by
Google.

Below is an example for Blogger...But I don't think Blogger (Google) let's you register using used user names, as they did before.
http://www.google.com/search?q=%22The+requested+URL+was+not+found+on+this+server%22+site:blogspot.com+intitle:%22Blogger:+404%22&num=20&hl=en&lr=&safe=off&client=firefox&rls=org.mozilla:en-US:unofficial&hs=qHq&filter=0

Here's an example using Blogster...Again, I don't think this still works for Blogster, either.
http://www.google.com/search?q=intitle:Blogster.com+%22The+blog+or+page+you+tried+to+reach+does+not+exist%22&num=20&hl=en&lr=&safe=off&filter=0

However, I'll bet there still some resources out there that this can exploit.

What you need to do is force substitue the domain for "blogger.com" and find the text used on the resource and use it inplace of:
22The+blog+or+page+you+tried+to+reach+does+not+exist%