In Firefox, when you type stuff into the main url bar (the "Awesome Bar") it tries to do a GoogleI'm Feeling Lucky search. So if you typed in wiki it would figure out you wanted Wikipedia and take you to Wikipedia.org, it would even take you to the localized version, and when it's in doubt it shows you a standard Google result.

To get this in Chrome add a custom search engine. Use the following as the url.

http://www.google.com/search?q=%s&btnI=Im+Feeling+Lucky

If you make it the default, then any keywords you type into the url bar (the "Omni Bar") will run an I'm Feeling Lucky search. Or you can set the keyword to l. So to use the custom search you would type in l wiki.