There are many poi groups on youtube.
Try
http://www.youtube.com/group/firepoi
You'll find some decent videos on there.
My tips for choreography are to use the whole stage. That means don't all stand in one place for the entire performance, but move around.
Think about body movement. Don't just spin the tricks with poi, think about how you can move your body to make them look more interesting. (A good video to look at is one of my (and many people's) old favorites ...http://www.youtube.com/watch?v=4AobaImsL3w)
And make sure you plan points in the routine where you can all catch up with each other. When spinning in front of an audience, its easy to get nervous, mess up a trick, get behind everyone else etc. When you're spinning in a group it is especially important to plan regular points in the routine which are fairly basic moves that people can 'catch up' with if they go wrong.
Good luck!
One last thing - have you thought about/got public liability insurance? If you're performing a public show, its something you need to get.