Bing is a search engine that finds and organizes the answers you need so you can make faster, more informed decisions.

DuckDuckGo is a search engine that prioritises its user's privacy and does not track your online activity.  

Metacrawler is a metasearch engine that searches results from several different search engines simultaneously.

Wolfram|Alpha is the first step in an ambitious, long-term project to make all systematic knowledge immediately computable by anyone.  Enter your question or calculation, and Wolfram|Alpha uses its built-in algorithms and a growing collection of data to compute the answer.