Some time ago I had the idea to write a google proxy which implements the features of the customizegoogle extension for firefox but should be browser and operating system independent. Today I stumbled across scroogle which apparently does implement some of the features (and uses ssl).
If you want to use it as default search engine in firefox, enter “about:config” in the location bar, search for “keyword.url” and change the value to “https://ssl.scroogle.org/cgi-bin/nbbwssl.cgi?Gw=”.
There are also search engine plugins available.