I get even more hot under the collar about stadia than kits, and there are many more variables about what makes a good stadium...

Firstly, you have the best examples of modern architecture:
Allianz Arena: http://sportlockerdotcom.files.wordpress.com/2012/04/allianz-arena-chelsea-colours-1.jpg
Stade des Lumieres: http://www.bfmtv.com/i/580/290/430788.jpg
Narodney stadium, Warsaw: http://www.poland2012.net/wp-content/uploads/2012/03/198775-the-national-stadium-warsaw1.jpg
Veltins Arena: http://www.smartbox.com/coffret2008/allemagne/302/DE_schalke006_ATU.jpg
Estadio do Dragao: http://farm1.staticflickr.com/53/121216404_5cfb974919.jpg

Then the huge shrines everyone (maybe) loves:
San Siro: http://www.thehardtackle.com/wp-content/uploads/2011/08/cculturalitaly.com_sansiro.jpg
Bernabeu: http://www.metropolitano-hotel.com/content/imgsxml/en/contenidos_lateral/santiago-bernabeu-full1.jpg
Azteca: http://footballtalkies.com/wp-content/uploads/2012/08/20120123-60040_estadio_azteca2.jpg
Maracana: http://c1038.r38.cf3.rackcdn.com/group5/building44276/media/ccuz_fernandes_estadio_maracana_torcida.jpg

And the quirky, smaller ones (old and new):
Estadio Municipal de Braga: http://4.bp.blogspot.com/_gJMCSTp8SGs/SpZ5b_mkQaI/AAAAAAAACXU/kqJP2iKk6EQ/s400/braga_stadium.jpg
Stockholms Olympic Stadium: http://userserve-ak.last.fm/serve/252/81188.jpg

Assembled this on an iPod, so apologies for any mistakes.