UFS CDROMs can be mounted directly on FreeBSD. Mounting disk partitions from Digital UNIX and other systems that support UFS may be more complex, depending on the details of the disk partitioning for the operating system in question.
As of 2.2, FreeBSD supports ext2fs partitions. See mount_ext2fs(8) for more information.
A read-only NTFS driver exists for FreeBSD. For more information, see this tutorial by Mark Ovens at http://ukug.uk.FreeBSD.org/~mark/ntfs_install.html.
Any other information on this subject would be appreciated.