Javascript can be a lot of fun, adding interactivity and cool effects to regular HTML pages. It's a little more complicated than HTML, but we've given some examples of the best things it can do.

pop-up windows: pop customized windows from links.
drop-down menus: use form drop downs for menus, both with a button or without.
chromeless windows: the very popular chromeless window.
mouseover images: change your link images when you hover over them.
no right click: disable the right mouse button to stop copycats.