This command will list the 15 largest in order:
du -xhS | sort -h | tail -n15
We use the -x flag to skip directories on separate file systems.
the '-h' on the du gives the output in human readable format, which sort can then arrange this in order.
the -S on the du command means the size of subdirectories is excluded.
You can change the number of the tail to see less or more. Super handy command.