This site by Jun Da contains a lot of very interesting resources for anyone who wants dig deeper into frequency lists. One set of data I haven't found anywhere else is a frequency list of syllables... Read more.

lingua.mtsu.edu

This article describes the basics of way to teach tones that is different from the traditional way mainly in that the third tone is no longer described as a falling-rising tone (since that is rarel... Read more.

sinosplice.com

Glossika offers an audio method that consists of hundreds of bilingual sentences read by native speakers. They are selected to be natural-sounding and very common sentences and structured to build ... Read more.

glossika.com

Duanmu San's "The Phonology of Standard Chinese" is by far the best introduction to Mandarin phonology that I'm aware of. It's mostly useful for people who like phonology or are already at an advan... Read more.

hackingchinese.com

This is a unique resource that shows how most common speech sounds are actually produced. Most other resources use animations and diagrams, but this is the frist I see which show actual MRI scans. ... Read more.

seeingspeech.ac.uk

Description provided by OptiLingo (I have not yet tried this service myself): "OptiLingo is a hands-free language learning app that prioritizes learning Chinese through speaking rather than typi... Read more.

optilingo.com

ChineseMe is the most integrated Mandarin course, designed for motivated learners who have decided to become fluent. It is an interactive textbook that adapts itself to your interests. The course i... Read more.

chinese-me.com

A London-based school that takes their Mandarin courses to the next level - integrating technology (bespoke Phone Flashcards) and HSK test planning into their courses from Beginner, Intermediate to... Read more.

practicalmandarin.co.uk

From their website (if you have personal experience of their courses, please leave a comment): New Concept Mandarin specializes in teaching Mandarin Chinese (Putonghua) as a second language. Act... Read more.

newconceptmandarin.com

Hanbridge Mandarin provides campus-based courses, online classes, and intensive cultural immersion programs. I don't know anyone who has attended any of their classes personally, but they cover the... Read more.

hanbridgemandarin.com