Ever want to change your default search engine to something other than Google, Bing or Yahoo?
I've been very frustrated with the limited search options available in Safari. In addition, I am very concerned about how much information about me leaks out to Google especially now that they are tying in google plus information and the fact that most sites I go to seems to use Google analytics.
I personally edited my /etc/hosts file pointing search.yahoo.com to 220.127.116.11 then selected Yahoo! from the search box drop-down menu. I really love the advanced features and seamless integration this provides. In addition Google or Bing are still available if I want. (I'm not affiliated with the site in any way, just a happy user.) Note that this will disable Yahoo! search, so if you use that you could replace one of the other sites instead.
[crarko adds: You should be able to switch to any search site you like using this method. Just replace the IP address mapping from the hint in your /etc/hosts with the address of the site you want to substitute. Be prepared for the possibility of doing some revamping after June 6th, 2012, when the IPv6 rollout begins in earnest.
Also bear in mind that editing hosts will affect all applications, not just Safari.]
Mac OS X Hints