ChineseClass101

http://www.chineseclass101.com

ChineseClass101 is a website devoted to teaching Mandarin Chinese. The free version has several different lessons for various learning levels. The premium version has more lessons and downloadable PDFs. They also have an app for Android devices and regular podcasts on Castbox.

Podcasts
Podcasts provide free lessons at a variety of levels in Mandarin.

Word a Day Emails
They send one word each day whenever you activate a free account with them.

Paid Membership
People can be paid members for 25 dollars a month and receive the all the full lessons provided by the website.