[gentoo-user] transparent compression? (e.g. device mapper for compression)

[Caveman Al Toraboran]

hi - any nice way to have compression at the file
system level, without using zfs?  perhaps some
kind of device mapper that compresses data?

i find file system compression to speed up
read/write to slow disks noticeably (e.g. sata).

rgrds,
cm.