to use the main address bar for custom searches on any site using a prefixed keyword, right-click on search boxes on websites and choose "add a keyword for this search...". the in the dialog under "Keyword" enter a character combination you seem fitting for use as a prefix for the search and close the dialog. now you can use the character combination as a prefix in the address bar, and everything following it is interpreted like it were written in the search box and pressing enter loads the results. you do not have to be on the source site for this to work. for example, right click the search box on wikipedia, choose "w" as the keyword and now anytime you type "w something" in the address bar and press enter it takes you to the search results for "something" on wikipedia