Another option is to use the keyword feature from Firefox. To set it up click the drop down arrow in the search bar, click on "Manage Search Engines...", highlight the Wikipedia entry and click on "Edit Keyword...", add something short and easy to remember such as 'w', click OK to both windows.
To do a wiki search just press ctrl+t to open a new tab, type the keyword followed with your search query and press enter. In my case that could be "w toms guide".
Needless to say this "trick" can be done with any search engine registered in Firefox. I use it heavily with Google.