In chrome, go to settings > manage search engines. Add a new engine with the parameters:

   name:wiki
   keyword: w
   URL: http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=inurl:en.wikipedia %s&btnI=745

Once saved, in chrome's address bar type "w foo" and press enter and you'll go directly to the wikipedia article on foo

By routing through google, it's also much more tolerant of misspellings.