/tell <name> <message> Sends a private <message> to player <name>
/village <message> (or
/v <message>) Sends a message to your village chat.
/addfriend <name> <category> Adds a friend.
/ignore <name> Ignore a player.
/invitations Allows you to receive an invitation from another player to join their kingdom or religion.
/who Shows who's currently logged in.
/mytemp Tells you your temperature and whether you're getting colder or warmer.
/seasons Tells you which harvestable is in season and when the others will be.
/time Tells you the current wurm date and time.
/caringfor Shows you which animals you're caring for.
/fsleep Activates or deactivates the use of your sleep bonus.
The list of wurm commands is quite extensive and it's not worth it to post it on many sites, so you can see the exhaustive list for example here.