Wondering if a Blog has an ROI

So here I go again, writing a blog.  I've played with this idea before.  I've done a few, and then I get too busy and stop.  I wonder the same thing about Twitter.  For the past several months I've done a variety of activities to determine whether there is any real value to spending time I don't have to do this very thing,
Well, I'm doing it, so I guess I see enough value to keep dabbling.  And over the past months I have come to learn that there are many great uses and absolute directed revenue that is derived from social networking.  Having said that, I believe that 90% of the tweets and blogs do not have a Return on Investment.  And that's OK,  As long as you take a realistic view of the outcome.
To be fair, I am not a social networking guru.  I don't have a huge marketing staff researching latest trends and tools and strategies.  But I am also not a guy who is addicted to Facebook or Twitter, nor do I think anyone cares what I ate for lunch.
I have however found real value as I've dabbled in this arena.  Specifically here:
1.  Research - What a great way to get realtime, current, feedback from folks on just about any subject.  What a great educational resource to watch how Microsoft has launched 7, or Google Voice, or you name it.  And then the point-counterpoint conversations that arise from real users,  Yes, I know they are not all who they pretend to be.
2.  Relationships - How else would I ever get to have a direct conversation or exchange with some of the most influential and visionary folks around the world.  It so helps from being in the cocoon of a large corporation and prevents group think.
3.  Global Thinking - I'm an IT guy.  I'm a healthcare guy. Solutions I look at have so much play around the world that it helps me think globally.  It's shocking how similar some of the challenges are in underdeveloped countries to the US.  A doctor in Iraq for example is an island of information. Is that any less true in the rural US?  When you show up in the ER, does the doctor know anything about you?
4.  Hearing the message - Sometimes I hear myself say something or see what I write - and it just helps me cristalize my message.
I will be exploring many issues in coming posts and commit to sharing with you my learnings along the way.