There are important differences between the pronunciation of American English and that spoken in Britain, Australia, Ireland and other English-speaking nations. As a result, it's better to focus on one country's accent. If that country is the US, these sites will be helpful.
Practice pronunciation, listening and grammar together! Choose from irregular verbs, adjectives, the alphabet and more! You can download the mp3 files.
LanguageGuide.org. Hover the mouse over the picture to read the word and listen to the pronunciation (American English). You can also see translations into many other languages.