You can perform general calculation directly from the search box. Like 15/3*2-1 etc. or 10 stones in kilos, 100 dollars in pound, 98 f to c, 420 in roman numerals,
You can search for meaning of any words directly from the search box as well. For example search for definition of fact as define:facts For this one google seems to be ahead of other browsers for better result.
Do you want to know the world time quick and easy. Just type time: and place you want to know the time of. Like this: time:nepal This will return the current time of Nepal. This is currently supported by google only.
Do you want to download MP3, Software, Movies etc lying around on the web hiding from us but not from search engines then do this to find what you want, may be you will be lucky to find it. intitle:"index.of" mp3 this will get you the list of MP3s direct links. Like that for movies you will type intitle:"index.of" Name of movie. You can use intitle: to search any web pages containing search term on the page title.
Similar to intitle: you can use inurl: to search words that appear on the url. inurl:cms will return search result that contain cms on the url itself. You can use this to find live webcams out there too. just try this: inurl:view/view.shtml
And, to search within body of websites intext:codefight.
Do you want to search for specific file types? For example you want to search for some free tutorials in pdf format. Then you can do so by using filetype:. e.g. make money filetype:pdf. This will search for pdf only. Also you can exclude filetype from the search by adding minus before filetype like: make money -filetype:pdf. This will search web for "make money" excluding pdf files.
You can find how many websites are pointing to your website by link:codefight.org.
To find related website as yours search as: related:codeigniter.com.
To find information about a website info:codeigniter.com.
To search within specified website only site:codefight.org. Also, site:.org will search org domains only.
To search movie reviews, trailors and showtimes do this movie: robin hood or film: robin hood, movie: showtimes.
To find quickly the director of any movie try this director: The Dark Knight. similarly casts as cast: moonlight
Similarly there are more options you can use such as music: band name, song etc, weather Kathmandu, population of Nepal, allinurl:cms, allintitle:cms tutorial, allintext:best cms, allinlinks:?codeigniter cms,
Also, don't forget to search "answer to life, the universe and everything".