Mac Spanish keyboard layout
If you are using Mac, you can set your keyboard to the Spanish layout. This makes it faster to type accents by simply hitting the "[" key and then the accented letter. Also, the ";" key becomes the "ñ" key.
Open System Preferences > Language and Text > Input Sources and choose the Spanish keyboard layout on the left. On the bottom right you can select "Show Input menu in menu bar" to be able to switch quickly between US and Spanish layout.
It puts the ¡ right next to the ! and the ¿ next to the ? so I think it's easier.