Simply post the md5 (preferably sha) sum next to the filename on your site or next to the torrent link.
If people care they can confirm that they got your book.
You can even do it in a clean cross platform way by using something like www.md5summer.org which is compatible with the output of GNU md5sum. Pretty cool even if your just moving some important files around and want to make sure....
As far as file distribution on p2p there are some halfway decents ways to do it now with something called a "magnet uri" this is essentially a url with an embedded crc32ed(so it works in a url) sha sum of the file your looking at.
If its setup right in your browser on windows it will launch gnucleus or something and start searching for the file based on the sum. At least in theory, it's a bit hackish since it's not integrated.
I hope that there is some interest in folding the concept into the gnutella protocol. It would be a tremendous advance for p2p in that it would allow Golive Books, Game Patches and Starwars Kids to be easily replicated throughout the net.
Just need to get people using the protocol. It would GREATLY benefit p2p to have a higher percentage of legitimate traffic on it... apt-gnutella or rpmfind-gnutella anyone?
Adam of the domain devtty.net