The site co-ordinator / space administrator is Chris Dillon.
He also provides grammatical explanations.
Jin Gao works on learning Chinese characters.
Selina Zhang provides character-explanations, examples and translations.
Binqian Cai contributed more characters and examples (especially measure words) and also conversations.
Tingting Wang answered tricky grammatical questions.
Reiko Nakazawa painted the pictures (including the ones on this page!).
Ting Zhang is contributing lots of sentences and conversations.