I don't know if it can be interesting, but it is possible (using Filepack and the OSDK) to compress some existing programs (the ones that are in one single file and 100% assembly code).
The advantage is that of course the program taking nearly only 50%-70% (depending of type of data) of it's original size, it would be way faster to load on tapes. And of course it would takes less room on a floppy too, so you can put more of these on one single floppy.
The idea is to appends the filepack unpacking code in front of the packed program, and then to get the first one to unpack the second one
Of course the load adress has to take into consideration the size of the loader.