It is like annotated bookmarks/favorites you store online and share with your friends.
I have been using it for about a month and it is fun and easy to use once you install it. With the Dude toolbar on your browser, you can then bookmark or "dude" items you like by clicking a button. The window then splits in half and lets you decide if you want to send it to other users or just mark it for yourself. You can drag in non-linky pictures and you can type in snarky comments for friends.
You pick an avatar and a name for your blog (mine is called PonyUp) and start a page of your links with pictures, comments, etc. listed in chronological order.
I like it because I am lazy and hate cutting and pasting URLs and downloading/uploading images. The app does it for you.
An additional feature is the "duderoll". You can choose who you want on your duderoll and pick people with likeminded interests and see what's struck their fancy that day.
If you dig something they have marked, you can click "dude it" and port it your own blog (The feature automatically logs where the link originated, so you get to give credit where cred is due).