Weasel is document reader for the Palm Pilot organizers. Weasel is Free Software released under the GNU General Public License v2. Unlike other doc viewers for the Palm, Weasel uses zTXT files as its primary format. These are similar in many ways to the de facto standard format, PalmDoc, but they feature much better compression. Weasel also reads PalmDoc files, though, so don't worry. It even supports bookmarks in both formats.
The zTXT compression is done using zLib, a Free compression library released under the zLib License. This results in much smaller files than with the PalmDoc method. For example, the Project Gutenberg e-text of "The Merry Adventures of Robin Hood" is approximately 600K in size. Compressed as a zTXT, it is only 261K in size, while with PalmDoc it is about 330K. Since the Palm Pilots do not have very much memory, this is a big savings.
After having an opportunity to use a Palm (IIIxe to be precise) for a couple months, I came to like them. Nice and small, light, and enough power to do quite a bit. A tad short on memory, but that was about it.
Eventually I decided that I would like to have one to use as a sort of eBook clone. I had used AportisDoc Mobile edition and noticed that (surprise!) it sucks a lot. Much of this apparent suckiness was due to it being the free version and being featured limited. I wasn't really looking forward to paying US$30 for an ASCII viewer for the Palm. There are other free viewers available, though, some of which are even Free (with a capital F).
Anyway, all the other viewers used the "open" PalmDoc format. Open only because somebody had reverse engineered it. Aportis wasn't very forthcoming. The problem is, PalmDoc is not very good for storing book length texts. Well... it's not that good for storing much of anything. The algorithm used is similar in ways to zLib (zip/gzip), but not nearly as advanced. What it does have, however, is speed. But, I'm willing to put up with a small decompression time when it means saving about 33% in space over PalmDoc (more the larger the text is). After all, most Palm's have only 8MB of memory or less. And the speed decrease is almost unnoticable in most cases.
So, I wrote Weasel Reader. You can get free e-texts from Project Gutenberg and read them with a free reader, Weasel.