I have posted some games featuring "Tango Tactics" arising out of the Black Knights Tango and related lines (including the Zurich Variation of the Nimzo-Indian). They make an excellent study aid for anyone trying to learn this line. You can also download the positions as a PDF file to print out and carry with you. In the positions above it is always Black to play and win, of course, by the quickest way possible. Additional games and puzzles are included in the links. For more info on the Tango, check out my 1...Nc6 bibliography.