Discuss Chinese language and culture. Feel free to talk about Cantonese or dialects in addition to Mandarin.
Resources for Learning Mandarin
learnnc.org
resources.allsetlearning.com
resources.allsetlearning.com
mdbg.net
gloss.dliflc.edu
Resources for learning Cantonese:
guidetocantonese.wordpress.com
cantonese.sheik.co.uk
cantonese.sheik.co.uk