I have a Spanish keyboard configured as such in Windows XP and in Arch Linux (XFCE).
According to the View menu, the key combination to open the console is **Ctrl+
**, but that combination doesn't work. I guess it's because is a dead key (i.e. it only works if you type something after it) in a Spanish layout. For example, to type it in this post, I have to press that key and then space.
I understand that using this key comes from a de facto standard in games and the assumption of a US layout. If so, games like HL2 for example still use the key to the left of the 1 key, even if using a keyboard with a Spanish layout.
Edit: the key to the left of the 1 key is º (no modifier), ª (with shift), \ (with AltGr). I changed the mapping of the console to Ctrl+º but it's still not working.
Edit 2: okay, I changed it to *Ctrl+* and now it somehow is working