[Carpetsmoker]

glabel(8) should work for FAT32, from the manpage:

Currently supported file systems are:

           o   UFS1 (directory /dev/ufs/).
           o   UFS2 (directory /dev/ufs/).
           o   MSDOSFS (FAT12, FAT16, FAT32) (directory /dev/msdosfs/).
           o   CD ISO9660 (directory /dev/iso9660/).
           o   EXT2FS (directory /dev/ext2fs/).
           o   REISERFS (directory /dev/reiserfs/).
           o   NTFS (directory /dev/ntfs/).

Which also answers the question where you can find the labels in /dev/.