Nice idea, but a few suggestions:
Use wikipedia's search function and returning the first result instead of just appending the query.
http://en.wikipedia.org/wiki/Special:Search?search= + query
If you don't decide to do that, at least replace spaces with underscores in the query.
http://en.wikipedia.org/wiki/Lord_of_the_rings exists, but "!wiki lord of the rings" says it doesn't.