Pronunciation
Sounds of American English
The University of Iowa's Sounds of English lets you pick sounds that you want to hear and see diagrams of how they are pronounced.
American English Pronunciation Practice: Minimal Pairs
Minimal Pairs Practice gives you the opportunity to choose between two similar sounding words.
Ship or Sheep
Here's a site for working on words with small differences (minimal pairs).
Longman's Dictionary of American English
Longman's Dictionary of American English has an online version. It requires free registration, but offers all of the features of the CD that is offered with the dictionary.
Kids are Cool
Kids R Cool is a Chinese site that offers English learning games. The pronunciation games time you and give you a chance to check your listening>
SpokenSkills
SpokenSkills allows you to listen to words and then record your own voice and compare it with the native speaker.
HowJSay: Instant Pronouncing Dictionary
Using a British accent, HowJSay plays the pronunication of a word.
Headway-Elementary
Headway- Elementary is an Oxford University Press site that includes tests, listening skills, grammar, and games.