Recently, one of my favorite firefox addons stopped working: CustomizeGoogle. This extension provided search suggestions when typing a query into google. Unfortunately, for some reason it stopped. After following the directions on the addon website and some additional fiddling, I was able to get it working again. Here's how:
Set http://www.google.com as your homepage, not the one with the Firefox logo on it
Disable Google Suggest in CustomizeGoogle.
Click on preferences on www.google.com and make sure "Provide query suggestions in the search box" is selected.
Click Save Preferences.
Clear your cache (without doing this it still didn't work for me).
EDIT: Doesn't seem to work with Google UK. More info can be found here.