I saw a lot of web site have a drop down menu. (microsoft.com, blizzard.com, gamespot.com,....)
onmouseover, then the menu will appear.
does anyone know how to do that??

or the simpler one,
a "+" sign on the left of options, click on it and some more menu will appear below it. and the sign become "-".

can anyone help me with these kind of effect?

Thanks

Cerebrate