This site contains thousands of print-friendly Chinese reference sheets, tests, revision aids and a unique Chinese dictionary called CantoDict. It is aimed to help you speak, read and write Hong Kong Chinese.  As such, the pronunciation given is not Mandarin 'pinyin' or 'Putonghua', it is Cantonese 'LSHK' or 'jyutping'.  
Having said that, many of the sheets, flashcards and tests will also help you learn Mandarin, as Chinese writing is the same in both Mandarin and Cantonese. Also CantoDict can run in both Cantonese and Mandarin modes.