This is obviously not a problem for everyone, but for those who type in different languages it might be useful. All the settings for language input are in System Preferences, to edit them go to:
Apple mark (in the top menubar) > System Preferences > Language & Text
a.) Language tab
Pretty straightforward, just arrange the languages in the order you use them.
b.) Input Sources tab
This is the important one. Select all the input methods you use. I use Japanese so I have selected Kotoeri which is the input method for Japanese characters on a Mac. Then within the Kotoeri sub-menu I choose the methods I prefer to use. I also like to have Unicode available just in case.
I always have my language input menu in my menu bar so I can see what language my keyboard is set to at any time. To do that you just click the box that says Show input menu in menu bar. Then it will show up like this:
c.) Language Hotkeys
If you want to change your hotkeys you can either click the button on the Input Sources tab or go to:
Apple mark > System Preferences > Keyboard
Click the Keyboard Shortcuts tab and from the side menu select Keyboard & Text Input. The ones you want are the bottom two
To change the hotkeys to suit you just double click on the current key combination and type the keys you want to change to. Make sure you hold down the keys otherwise it will just take the first key you press. It saves automatically.