A great way if you have a bunch of drives and mdadm connected and are looking for backups/archives and don't know what is where!
for md in `cat /proc/mdstat|grep md[0-99]|awk '{print $1}'`; do mkdir /mnt/$md; mount /dev/$md /mnt/$md; done
mount, mdadm, arrays, automaticallya, backups, archives, md, proc, mdstat, grep, awk, mkdir, mnt, dev,