ZFS, which (sort of) stands for Zettabyte File System and was originally developed by Sun, is a huge step forward from traditional file systems. It protects all files with 64-bit checksums to detect and fix data corruption and, as a 128-bit file system, can handle many orders of magnitude more space than current versions of Microsoft Windows, OS X, or Linux. (There is a movement afoot to port ZFS to Linux but it's complicated by restrictions in the GNU General Public License.)
One of the biggest changes ZFS offers is what's known as a pooled storage model. What that means is that physical drives become even more removed from logical volumes, and getting more free space simply means plugging in more drives. The file system takes care of the rest for you.
ZFS also offers snapshots of the state of a file system at a particular time, handles RAID-type backups automatically, and offers optional compression. Here are 10 reasons to reformat your hard drives with ZFS.
Perhaps the best thing about ZFS, though, is that its 128-bit limit should last for quite a while. One post calculated that fully using that much storage (2^128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 bits) would require more energy than it would take to boil Earth's oceans.