on the fly file system compression

Hi all, I am looking for a way to compress a whole partition or some files on it on the fly. I want to use this partiton for backup. Ext3 has an inofficial patch to kernel and userland tools to allow on the fly compression, but as they state themselves, it is not ready for end user, I do not really want to use it. another idea I have is to have a file mounted via loopback device. Do I can have a file in a compressed state. e.g. image.gz and mount that via loopback? or can I do another different filesystem that can handle compression? any input appreciated. kind regards Sebastian