The New York Times contains every article, fully searchable, published in the New York Times since 1851. First, set up an account (instructions here). Then just connect to nytimes.com and login. Or, once you have your account set up, download the NYTimes app from the app store. For more information on setting up an account and using the iPad app, see the New York Times Subject Guide.
http://www.nytimes.com/