Website Review: accentmaster.com
In short: They sell software or lessons to help students improve their accents. The software is different depending on your language (so you don’t waste time practicing sounds that are easy for you). In addition, they don’t just focus on making sounds, but also on things like intonation and word stress.
For students: This software (or the lessons) will definitely help you improve, but if it’s too expensive, remember to listen to as much English as possible and try to repeat what you hear. When you repeat, focus on the sounds, but also on intonation, word stress and timing. Try to copy things exactly.
For teachers: Check out the YouTube site at youtube.com/user/AccentMasterLynn. Unless your students have a pretty high level, these’ll be too tough for them to understand, but you can learn a lot about what’s important when teaching speaking.