Charles I. Kelly and Lawrence E. Kelly
American English Pronunciation Practice Minimal Pairs
24 lessons based on words that sound similar in English, e.g., they/day, see/she, said/sad. Practice listening to and saying each pair, then listen to a sentence and identify the word used.
English Zone
English zone.com: Pronunciation Zone
Pronunciation practice site from English-Zone.com. A short lesson about pronunciations followed by pronunciation quizzes. Some free content; subscription-based access otherwise.