I am sure there are a lot of people reading this who think "how is this different than blogging?" I'd like to suggest that everyone try this
I blogged earlier about a simple way to give twitter a try (here and here) and think that both of these need to be experienced to get a sense of what they are like. There's something about the ambient nature of twitter (think the value of fb status updates amped up). It's of course much more than that and I'm finding tumblr encourages me to explore and share creatively. So much of it has to do with the sharing of pictures, videos, music, and quotes that I'm finding it interesting to watch what it is that interests me in what I'm posting or reblogging. I think it keeps me on the frontier - exploring things that I can't quite articulate yet and certainly finding things that have prompted a breakthrough in my thinking in ways never intended.
Give it a try - both twitter and tumblr and add me if you do (igniter on twitter and igniter.tumblr.com on tumblr).