For the last year or so at Tieto (which I just left on August 31st, in preparation for my returning home to the United States) I used an online micro-blogging site, Yammer, with my company account. Someone in Tieto in Europe had already set up a company "network" within Yammer and somehow I found out about it (I don't remember, maybe I read it on the company's internal blog or somewhere).
It was fun, I enjoyed it. There were occasional technical discussions and a sometimes helping others with Java and sometimes getting help from others where I was stuck. Most of the discussions had to do with bigger corporate things, like knowledge management, about which I don't know a whole lot, but interesting to read ideas from some very smart, very skilled people.
Most days I posted something when I first got in, "ah, Tuesday..." with a bit of a description about my commute to work, or something about life in the office in India. Some was for me to vent, some was just things I figured someone who hadn't worked in India would find interesting about working in India. While there was rarely any follow-up comments from others, I got a few emails in private that people enjoyed reading those, so that felt pretty good, especially since I enjoyed the writing.
Probably what I got most out of it was finding out that Tieto does more than just the project I worked on, and the few physically around it. I mean, I knew that, but had no idea what the rest of this company was other than "they" or "everything else". It turned Tieto from a gigantic company of mostly totally faceless "other" people into a bunch of people I never worked with but were real people.
Before using Yammer I knew that Tieto was quite big, but the only things I saw were my project and some of the other ones at the Pune office, which is only a tiny fraction of what Tieto does. And the people I interacted with were only a tiny portion of Tieto's 17,000 "experts" (as we were all called). And after I found there were a lot of good people there, and while my team was fantastic there were others I'm sure I'd have enjoyed working more closely with as well.
So, I'd recommend Yammer for anyone who works in a company or organization that's too big for everybody to know everybody else.