I am contemplating doing "interactive" tutorials on a website i'm developing

The point of this would be the first time a user visits a specific area or functionality of a site, or if they click help an interactive "session" could start, that guides the user hand in hand trough a series of steps, buttons would be highlighted with an arrow or some other kind of indication, i'm thinking in the ways of some game tutorials that exists.

i'd think you would need to be able to assign "tasks" the user needs to peform to get to the next step of the tutorial like

* Click this button (arrow pointing)
* Write 'something' in this field (arrow pointing, perhaps automaticly starting to write it as an example)

And then assorted ways of display notes or areas of interrest together with the notes, dimming parts of the screen. anything like this exists or would I have to start writing something like this from scratch? :)

Wondered if a jquery plugin for some sort of tutorial framework exists, alternatively if anyone has any ideas they would be welcome.