Well done Danne on organsing the tourney! You did well to finish second!
My belief for future online tourneys is that we just see how enters the room on the night even if they havent confirmed their attendance. See how many people turn up and then have a brief discussion on if people want a cup or whatever. Try and involve everyone - if they want to be. Try not to allienate people.
But thats just my opinion and if people make the effort to organise their own tournament then they have right to make whatever rules they wish. But I think one thing is for certain..in this age where there's not enough hours in the day...a quick PM to people who have indicated an interest to make sure they dont forget is a must. (I would say that though hehe)
I know you asked for suggestions but I purposely didnt suggest anything because I wanted this to be your online cup mate, not anyone elses. I was there to try and help people with servers I know about.
But the main thing is mate is that you organised this and people had fun. I hope to play again when you organise your next tourney.