From now on, you can access a random post by using the "next post" button on any post of that category (eg Pic posts will take you to another pic post)
1. Locate your browser's Bookmarking Bar. Most browsers have these now. Its a bar that contains some of your bookmarks (or "favourites", if you are an IEfag).
Random Picture Post
Random Video Post
Random Flash Post
Note: Bookmarklet is a term used to describe something that you put in your bookmarks, but works more as a utility rather than an actual page you visit often.
Also, this feature was technically removed. When the "favorites" feature was added, the random button was replaced by the Favorites button. I'm not sure if this was done for a technical reason or not, but i thought it would be useful to have back.