Wikipedia

Wikipedia is being created simultaneously in several languages. It has become a very common reference for many active internet user in the US. I'm not sure how popular it is outside of the US.

Portugal is a signator of to the Schengen Agreement. Here are the other members (a copy and paste from Wikipedia)
Membership

* 14 June 1985 - Belgium, France, West Germany, Luxembourg, Netherlands
* 3 October 1990 - (German reunification brings in the former East Germany)
* 27 November 1990 - Italy
* 25 June 1992 - Portugal, Spain
* 6 November 1992 - Greece
* 28 April 1995 - Austria
* 19 December 1996 - Denmark, Finland, Iceland, Norway, Sweden, or the Nordic countries. Through the Nordic Council, they have an even more permissive agreement on internal movement of persons.
* 29 May 2000 - Republic of Ireland, United Kingdom (both countries limited membership only)
* 1 May 2004 - Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, Slovenia
* 16 October 2004 - Switzerland (ratified by referendum on 5 June 2005)
* 1 January 2007 - Bulgaria, Romania

This is a map, that shows the members.The palest of colors are nations that are not members.