There are so many commands, and the the server won't tell you if what you are typing is a legal command or nut until you complete it. A full list of every command, as well as a description of what each one does, would be a great addition to the Survival spawn area, maybe in one of the houses. Doing /help only provides you with a few of the commands.

I will make a list of all the ones I know when I have time.