this is how to get "¿"

[Apokalipse]

hold alt then press 168 (on the numpad) then release alt and you get "¿"

you can use different numbers as well to get different symbols

ô = alt+147

«ô¿ô»

 

[Martin]

You can look in the Character Map (Start Menu > Programs > Accessories > System Tools) for a complete listing of all ASCII characters.

 

[Apokalipse]

and there are Internet sites you can search to tell you what you can make and what numbers you have to use to get them (alt+xxx)