Not a tool per se, but the file system supports compression of entire volumes with lzo or zlib. There's been proposed others, and some is already in the works ( https://btrfs.wiki.kernel.org/index.php/Compression ).
It is also a part of the Linux kernel.
Ranked in these QuestionsQuestion Ranking
Pro Easy to manage
Just one userspace tool, with which one can manage the entire filesystem, volumes, and subvolumes, create snapshots, change quotas, and more.
Pro Good compression
While LZO is by far not the most effective compression algorithm, running it on a per-volume basis allows larger volumes to be shrinked quite well, which in some cases may also increase I/O throughput.