Tumblr is a new blogging platform which focuses on simple, quick blogging called tumblelogs. A tumblelog is a blog of very short posts, maybe just a photo, link or quote; a slightly richer form of Twitter.
The Tumblr service has an elegant design focusing on simplicity. I was impressed with it and for a few days switched my mkaz.com blog over. However, after just a few posts I found the simplicity a little stifling and I wanted to be able to do a few other things, such as align photos, use categories and an organized archive.