CmdOrCtrl is the command key on Apple keyboards or the ctrl key on PC keyboards.
h / CmdOrCtrl+Shift+] : tabs left
l / CmdOrCtrl+Shift+[: tabs right
x / CmdOrCtrl+w : close tab
CmdOrCtrl+Shift+w will close the current window
j : next message (down)
k : previous message
o : open message thread (and scroll to position of this message in that thread)
: toggle raw message view for currently selected message ( = backtick, lives on the same key as ~)
composing : cttrl + enter = post
@ : start a person query
# : start a channel query
? : start a search query
/ : start a navigation (e.g. /public) - need to re-instate suggestions for this
you can also paste a message id (starts with %) in here to navigate to it. Same with blobs (&)