By the way, a new encrypted file could be sent each time someone logs into a game and the decryption key sent when logged out (or after a certain time period you are sent it and a new encrypted file sent at the same time). There are many ways of doing this. Even just sending one result at a time as eek mentioned isn't a bad idea either because at least it proves the result is independent of the bet size and player decision.
You could even send it in such a format so that it works for all the games and not just one separate file for each game but this would probably be more complicated for the player to understand but at least it wouldn't look so predetermined for some players because playing different games will alter the order of the results.The file could even decrypt automatically with no other program needed (asks for a password when opened and then show the results as a text file).
I have discussed this before with the Philip Kissane who is the head of Littlewoods Online Casino. The first time was in late 2002 and they didn't think it was logistically possible but I don't see why not. I even have a thread here:
http://www.faircasinos.com/forum/viewtopic.php?t=31 about it but didn't want to describe it until I had a demonstration ready.