exec sp_stored_procedures

That's it. That single line/word will list all the stored procedures in the currently-active database. 

DatabaseName.dbo.sp_stored_procedures

This line lists all the stored procedures in the specified database.

Another useful stored procedure is sp_helptext, which shows you the actual (SQL) stored procedure: 

DatabaseName.dbo.sp_helptext StoredProcedureName

Using these stored procedures with a linked server is straight-forward, too:

NameOfTheLinkedServer.NameOfTheDatabase.DatabaseOwner.sp_stored_procedures