As an introduction, here is a nice compilation of Argentinian tango illustrated by clips from old Argentinian films from the 1930s:
The legendary Francisco Canaro and his orchestra (and two of the famous vocalists of that time):
Tango is, of course, great for dancing. If you would like to improve on your dancing skills, this couple shows what you can do:
For those who would like to know more about the history of tango this is an excellent site.