Chris Pirillo has been trying googlefasting, which is quite interesting since I have thought about and even tried in the past( and failed !!! ). My search engine of choice was Yahoo! ( no surprise there ) but it just didnt cut it. A feeling you always get is that maybe your missing out on something from the search results and then you end up going to google
Conclusion: You can stay away from their services like mail, maps, but when it comes to search it is very difficult to replace Google. Maybe if Yahoo improves on its mindset feature switching could be a little more easier.