Here is a list of all the server commands accessible to all players and to members. I'll update this list as I can, or if I've missed something please PM me.
A quick note: I will list all the commands here only in the chat form, but most can be used in console using sm_ instead of !. All of the commands can have their text output suppressed by using / instead of !.
Commands accessible to all players:
-- -- --Miscellaneous-- -- --
!ready, or !r; Tells the server that you're ready