Here are some of the most useful links I have found for accent reduction:
Rachel’s English: Videos showing how to produce different speech sounds.
Speak Canadian English: This links to sample exercises, working on some common difficulties for people learning English: the sounds “th” and “r,” the vowel sound “i” (in “sit” and “pin”), and the contrast in stress patterns in nouns and verbs that are spelled alike (such as the verb “permit” and the noun “permit”).
Interesting Things for ESL Students has a lot of good material. My favourites are below:
Audio Concentration Games: Match up cards by listening to the words – great practice for distinguishing between similar sounds such as “i” and “ee.”
Daily Listen and Repeat: Daily exercises to practice intonation, rhythm and pronunciation. Listen and Read Along: Lots of interesting articles adapted from material by VOA.
News in Levels: Written English-language news stories, at three different levels of difficulty.