Tumblr is a micro-blogging platform that enables easy combining of text, images and video; it also makes it easy for multiple users to contribute content to a topic or thread, where the content 'tumbles'...
One of many Ryan Gosling 'Hey Girl' TUMBLR threads, this one for runners:
Another example of a TUMBLR blog: Awesome people hanging out together
And one more, I Love Charts, a TUMBLR blog devoted to all kinds of charts:
And here's an example of how a storyteller can combine content types (text, images, video) in a TUMBLR blog. This is my TUMBL blog of the KGW -TV Hood to Coast Relay team, posted in real time as we ran from Mt. Hood to the Oregon Coast: