How about the links? Any blog of any size has links - usually within the blog, and outside the blog. Maybe links to other blogs produced by the same person, to the close friends of that person, and to acquaintances and strangers.
OMG, Chuck, that could take days. I don't have time for that nonsense.
But that nonsense can be a key to finding a contact to a friend or stranger, or a problem in your own blog. And maybe you do have time, if you automate your research.
IT-Mate provides a free useful product - vURL Desktop Edition - that walks through any blog or website, extracts each link, and presents you with an alphabetised and normalised list of all links found. You can look at the list presented to you, and find other links within that blog, to other blogs, and to other web sites. Along with the link list, it provides a listing of the source code, similar to a "View - Page Source" command in Firefox or Internet Explorer.
For each link that interests you, a (right click of mouse) context menu offers many options, such as opening the site in your browser, or running another copy of vURL against that web site.
Once you have a list generated by vURL, you can examine the blogs in the list using hpObserver Site Online.
Combining vURL and hpObserver, you can parse and monitor a lot of Blogger blogs.
Another useful product is Sala's HTML Graph Applet, which gives you a stylised picture showing the node structure of your blog or web site.