http://www.learnenglish-online.com/grammar/tests/superlativecomparative.html
http://www.ejerciciosinglesonline.com/new-exercises/ex-comparative-superlative/
http://www.agendaweb.org/exercises/grammar/comparison/comparative-superlative-4
http://www.adelescorner.org/grammar/comparatives/superlatives.html
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjectives_comparison_as_as.htm
http://www.englishexercises.org/makeagame/viewgame.asp?id=1833
List of comparative + superlative adjectives
http://www.curso-ingles.com/recursos/cheat-sheets/adjectives/list-of-comparatives-and-superlatives
Comparatives - presentation